Sybase SQL

Introduction

Sybase SQL Server 11 - Has a Single-Process, Multi-threaded Database Engine - Includes a query optimizer Standard SQL: * DDL (Data Definition language), * DML (Data Modification langiage), * DCL (Data Control Language) Transact-SQL = SQL + flow-control (if and while), local variables, etc.. 4 main verbs: select, insert, update, delete. But even before these words - here are some often used commands (working ( working with Sybase:

FUC - Frequently Used Commands

isql -Sserver -Uuser -Ppassword 1> use some_database 1> select db_name() 1> select @@servername 1> select user_name() 1> sp_helpdb 1> sp_helpdb dbname 1> sp_help 1> sp_help tablename 1> set rowcount 2 -- to limit number of rows 1> set rowcount 0 -- remove rowcount limitation 1> select * from sometable where 1=2 -- to see column names 1> vi -- to edit command 1>select name from sysobjects where type = " V" 1> quit Here are useful help commands: select name from sysobjects where name like "sp_help%"

SELECT select from select au_lname, au_fname from authors select title_id, type, price, price * .1 from titles select * from publishers string concatenation: select au_lname + ", " + au_fname from authors name ouput columns yourself - column alias select title_id, type, price "original price", price * .1 discount from titles select "Full Author Name" = au_lname +", " + au_fname from authors remove duplicates with distinct with distinct:: select distinct type from titles select distinct city, state from authors (here distinct refers to a combination of city and state, so that each column by itself may have duplicate entries) filtering rows with where select from where select au_lname, au_fname from authors where state="CA"

equality and inequality operators: = , <> or != , > , >= , < , <= , !< , !> select type, title_id, price from titles where price * total_sales < advance (can be applied to string comparison - default sorting sorting order is ASCII) logical OR and AND and AND select au_id, city, state from authors where state="CA" or city="Salt Lake City"  between and Ranges of Data: between and select title_id, price from titles where price between $5 and $10 equivalent to select title_id, price from titles where price >= $5 and price <= $10  not between: select title_id, price from titles where price not between $5 and $10 equivalent to select title_id, price from titles where price >= $5 and price <= $10 in (...) : select title_id, price from titles where type in ("mod_cook", "trad_cook", "business") equivalent to select title_id, price from titles where type = "mod_cook" or type = "trad_cook" "tr ad_cook" or type = "business" not in (...) select title_id, price from titles where type not in ("mod_cook", "trad_cook", "business") wildcards with like: % - any number (0 to many) of any characters _ (underscore) - any single character [ ] any single character from those listed in the brackets brackets (this is only only for Sybase) [%[ - actually match the % character [^A-C] - matches any character except A,B,C

select au_lname, au_fname, city, state from authors where city like "Spring%" select type, title_id, price from titles where title_id like "B_1342" select type, title_id, price from titles where title_id like "B[A-Za-z0]1342 Note - if you need to include the '_' character in your pattern - use 'escape' word, for example: select * from titles where title_id like 'ABC\_%' escape('\') ordering result sets with order with  order by: by: select au_lname, au_fname from authors order by au_lname select au_lname, au_fname from authors order by au_lname, au_fname  order by position in the select list: select title_id, price, total_sales, price*total_sales "total dollar sales" from titles order by 4 Ascending and Descending Ordering select title_id, price, total_sales, price*total_sales "total dollar sales" from titles order by price*total_sales desc default sort order is ascending. Example: sort by type (ascending) and then by total_sales (desc): select title_id, price, total_sales from titles order by type, total_sales desc order by columns not Appearing in the Select List: select au_lname, au_fname from authors order by city, state agregate functions: sum( ) - total numeric, avg( ) - average numeric,

min( ) - lowest numeric or sorting string or earliest date, max( ) - highest numeric or sorting string or latest date, count( ) - returns the number of non-null expressions, count(*) - returns number of rows found select avg(price) from title select avg(price) "avg" from titles where type = "business" select avg(price) "avg", sum(price) "sum" from titles where type in ("business","mod_cook") counting rows with count(*): select count(*) from authors where state="CA"

agregates functions discard null values sub-agregates with group by: select type, avg(price) "avg", sum(price) "sum" fro m titles where type in ("_business", "mod_cook") group by type When two or more columns are included in group by statement, agregates are based on unique combinations of these columns: select type, pub_id, avg(price) "avg", sum(price) "sum" from titles where type in ("_business", "mod_cook") group by type, pub_id

In order for aggregates to properly subtotal (or subaverage or subcount) by non-aggregate values, all non-aggregate columns in the select list should be repeated in the group by clause (see color above). Filtering results with having: where - selects rows before averaging: select type, avg(price) from titles where price > $10 group by type having select rows from the result set: select type, avg(price) from titles where price > $10 group by type having avg(price) > $20

Example: find duplicates of au_id: select au_id, count(*) from authors group by au_id having count(*) > 1 Worktable - a temporary table which is created before distinct, having or order by are applied. select type, avg(price) from titles where pub_id="1289" group by type having avg(price) > $15 order by avg(price) desc

JOIN JOIN Operations:  join using common key (or join key): select title, pub_name from titles, publishers where titles.pub_id = publishers.pub_id

select title, pub_name from titles t inner join publishers p on t.pub_id = p.pub_id select au_lname, au_fname, title from authors a, titles t, titleauthor ta where ta.title_id = t.title.id and a.au_id = ta.au_id and type="psychology"

select t.*, pub_name from titles t, publishers p where t.pub_id = p.pub_id Outer join: left (*=) or right (=*): select pub_name, title from publishers p, titles t where p.pub_id *= t.pub_id and ...

select pub_name, title from publishers p left outer join titles t on p.pub_id = t.pub_id where ... This query retrieves all pub_names from publishers. For any row that doesn't join successfully with titles, the title column will contain a null for that row in the output. Subqueries - to be used instead of a constant: select title from titles where pub_id = ( select pub_id from publishers where pub_name = "Algodata Infosystems") Subqueries with IN (or NOT IN ) can return multiple rows: select pub_name from publishers where pub_id in (select pub_id from titles where type = "business") subquery can be rewritten as a JOIN : select pub_name from publishers p, titles t where p.pub_id = t.pub_id and type = "business" Subqueries with exists - the best way to eliminate duplicates: select pub_name from publishers p where exists (select * from titles t where p.pub_id = t.pub_id and type = "business")  not exists and not in : select pub_name from publishers p where not exists (select * from titles t where p.pub_id = t.pub_id and type = "business")

Unfortunately the "not exists" construct runs very slowly. A better (much-much faster) way (in 12.5) is to use the new syntax: select pub_name from publishers p left outer join titles t on p.pub_id = t.pub_id and t.type = "business" where t.pub_id is null This following syntax I don't like - create problems (char/varchar, nulls): select pub_name from publishers where pub_id not in (select pub_id from titles where type = "business") Subqueries with agregates in the where clauses: select type, price from titles where price < (select avg(price) from titles) union operations: select city, state from authors union select city, state from publishers

(duplicates will be automatically removed from t he result unless you use union all ) Here is one more example: select 95 "year", month, sum(dollar_sales)

from salescurrent group by month union select 94 "year", month, sum(dollar_sales) from salescurrent group by month order by year, month

select into, insert, update, delete Using select into: creates a table on the fly instead of returning the the output to the user: select distinct type into type_lookup from titles

Example: create an empty copy of an existing table: select * into new_salesdetail from salesdetail where 1 = 2 Adding rows with insert: insert authors (au_id, au_lname, au_fname, phone) values ("123-45-6789","Jones","Mary","212-555-1212")

Columns that are not specified will be set to their default values If you don't specify column names at all (which is very bad practice and dangerous) - then you have to provide values for ALL columns an in the right order: insert publishers values ("1235","New World Printing","GA","Atlanta")

inserting several rows with select: insert authors_archive (au_id, au_lname, au_fname, phone, city, state, zip) select au_id, au_lname, au_fname, phone, city, state, zip fro m authors where state="CA" modifying rows with update: update publishers set pub_name = "Joe's Press" where pub_id = "1234"

Example: update based on a join: update titles set full_name = isnull(u.full_name,'') from db1..titles tit, db2..users u where tit.kid *= u.kid Example: double all prices in the table: update titles set price=price*2 update several columns simultaneously: update contacts set address1 = "5 W. Main St.", address2 = "Apt.3D", state="CT", zip="03838" where contract_id = 17938 remove rows with delete: delete titles where type = "business"

Clearing the table: delete title or truncate table titles

truncate is faster, but it doesn't log individual deletions - thus the ability to recover database is compromised.

Datatypes Datatypes: Once you create a column of certain datatype - you can not change it without dropping and re-creating the table ????

create table my_table ( id int not null value float not null description varchar(30) null ) Storing strings: char - fixed length strings (max length - 255) varchar - variable-length strings (max length - 255) nchar - multi-byte character strings nvarchar - variable-length multi-byte char strings text - for very large strings (up to 2 GB of text per row) Storing binary data: binary - for fixed-length binary strings varbinary - for variable-length binary strings image - for storing large binary strings (up to 2 GB of image data per row)

insert b_table (id, bin_col) values (19, 0xa134c2ff) using timestamp: create table timestamp_example ( id int not null, code char(3) not null, ts timestamp not null )

insert timestamp_example (id, code) values (17, "AAA") The server uses the unique transaction-log-row id as a timestamp. You can not specify this value. Optimistic locking: using tsequal() function to check the locking

Storing BLOBs (binary large objects) using text and image datatypes: create table texts ( id numeric(5,0) identity, item int not null, textstring text null ) using insert:

insert texts (item, textstring) values (1, null) insert texts (item, textstring) values (2) insert texts (item, textstring) values (3, "some text") insert texts (item, textstring) values (4, "some very long text") insert statement will not insert more than 1,200 bytes. string concatenation on strings longer than 255 chars is illegal

using writetext and readtext: The idea is to get the pointer to the text chain and to write directly to this chain without modif ying the underlying row. To do this you should start with a non-null popinter stored in the ro w itself.

Here is how to retrieve the pointer for a row: select id, textptr(textstring) textptr, datalength(textstring) datalength from texts to write a new textstring value to the 3rd row: declare @pageptr varbinary(16) select @pageptr = textptr(textstring) from texts where id = 3 writetext texts.textstring @pageptr "some very long string" to read 50 bytes starting from position 4000: declare @pageptr varbinary(16) select @pageptr = textptr(textstring) from texts where id = 3 readtext texts.textstring @pageptr 4000 50 textstring Date/Time datatypes: datetime (3 millisecons, 8 bytes) smalldatetime (1 min, 4 bytes)

create table date_example ( id int not null dateval datetime not null) insert date_example (id, dateval) values (19, "September 25, 1996 3:15PM") you can use other forms of format, for example: 4/15/99 select * from date_table where date = "9/3/95" select * from date_table where date >= "9/3/95" and date < "9/4/95" timestamp - a binary, ticks of some sort, it is not datetime drop table #test create table #test ( id numeric(18,0) identity, ts timestamp, dt datetime, sm smalldatetime ) insert #test(dt,sm) values (getdate(), getdate()) select * from #test datediff(dd,"15-Apr-2000","15-Apr-2001") - returns '365' where LastActivityDate > dateadd(yy,-2,getdate()) where LastActivityDate > dateadd(dd, -90, getdate())

Logical datatype: bit - can not be indexed and can not be null: create table bit_sample (id int not null, description varchar(30) null, active bit not null) Numeric datatypes: int - 4 bytes signed smallint - 2 bytes signed

tinyint - unsigned byte (0..255) float - 8 bytes real - 4 bytes numeric(7,2) - you can indicate total number of digits and number of digits after decimal point. Can be used with identity (automatic counter) decimal - similar to numeric, but can't be used with identity money - 8 bytes smallmoney - 4 bytes (+/-214,748.3647)

create table numeric_example ( id numeric(8,0) identity, num_col numeric(7,2)) insert dollar_table (id, dollars) values (95, $12345.93) ================================================================================= create table table_name ( ...) drop table table_name sp_help sp_help table_name object's full name: database_name.owner_name.object_name

pubs.dbo.authors Columns can have following properties: Null, Not null, Identity

Views and Temporary Tables

Views - logical way of looking at data (you can treat them as tables): create view author_name as select last = au_lname, first = au_fname from authors select * from author_name drop view author_name

* note: dropping a view doesn't change data * views - help security by limiting access to tables * views - help make queries simpler * views can contain aggregate functions and grouping, joins, other views and a distinct clause. * views CAN NOT include "select into" , a compute clause, a union clause, and "order by" clause. * You can insert into, update and delete from views (restriction: allowed to affect only one base table). * If view includes columns from several tables, you can't delete rows from view or update columns from more than 1 table in a single update statement * You can not update, delete or insert into a view containing the distinct clause. sp_help - lists all objects (including tables and views) to get a list of just the views: select name from sysobjects where type = "V" to see a list of columns in a view: sp_help view_name Renaming objects (tables, views, columns.) using  sp_rename: sp_rename old_name new_name sp_rename 'table_name.old_col_name' , 'new_col_name' Adding columns to a table using alter: alter table tt add middle_name varchar(20) null, fax varchar(15) null

NOTE: You can only add columns with null values. NOTE: You can't remove columns using alter. You have to recreate the table and indexes and insert data again, for example: create table lev1 (c1 int not null,c2 int null) CREATE UNIQUE CLUSTERED INDEX lev1_idx ON lev1(c1) CREATE NONCLUSTERED INDEX lev1_qib_idx ON lev1(c1,c2) insert lev1 values (1,2) insert lev1 values (2,2) insert lev1 values (3,2) ------- add columns ----------------alter table lev1 add c3 int null, c4 int null ------- remove columns ------------exec sp_rename 'lev1','lev1_tmp' -- sp_rename 'lev1_tmp.lev1_idx', 'lev1_tmp_idx' -- sp_rename 'lev1_tmp.lev1_qib_idx', 'lev1_tmp_qib_idx' create table lev1 (c1 int null, c2 int null) CREATE UNIQUE CLUSTERED INDEX lev1_idx ON lev1(c1) CREATE NONCLUSTERED INDEX lev1_qib_idx ON lev1(c1,c2) insert into lev1 select c1,c2 from lev1_tmp drop table lev1_tmp -- this will automatically drop indexes Temporary Tables - are real tables created in the tempdb database. They have '#' before table name. They exist only for the duration of a user session (or stored procedure) and only accessible to this session. These tables are not recoverable (in case of a crush). select au_lname, au_fname, title, pub_id into #titles_and_authors from authors a, titleauthor ta, titles t where a.au_id = ta.au_id and t.title_id = ta.title_id

Creating permanent Temporary table in tempdb: select * into tempdb..titles from pubs2..titles

Rules & Defaults

Rules: create rule order_quantity as @quantity between 100 and 150000 create rule color_rule as @color in ('black', 'brown', 'red') create rule pub_id_rule as @pubid like ('99[0-9][0-9]') or @pubid in ('0736', '0877', '1389') create rule date_rule as @date >= getdate() drop rule key_rule Binding rule to a column: sp_bindrule rule_name, 'table.column_name' sp_unbindrule 'table.column_name' Defaults: create default country_default as 'USA' create default age_default as 16 create default time_default as getdate( )

binding default to columns in a table: sp_binddefault default_name, 'table.column_name' sp_bindefault country_default, 'demographics.country' sp_unbindefault 'demographics.country'

you can define default for a column when you create a table. later you can change it using later table: alter table items replace price default null alter table items replace item_code default "N/A" To list all rules and defaults in a database: select name from sysobjects where type in (" R", "D")

To examine the rules and defaults bound to the column in a table: sp_help table_name sp_helptext object_name Creating User-defined Datatypes: sp_addtype ssn_type, 'char(9)', "not null"

Indexes and Constraints

Indexes: 2 types of indexes - clustered and nonclustered. Both are B-tree. Clustered - only one clustered index per table can exist (data is maintained in clustered index order). Nonclustered indexes - you can have 249 of them per table. They maintain pointers to rows (not data pages). An index can contain up to 16 columns, but toal index width <= 255. Creating indexes: create unique clustered index name_index on authors (au_lname, au_fname) create index fname_index on authors (au_fname, au_lname) ***********************Constraints: Primary Key and Unique Constraints Check Constraints Referential-integrity Constraints Primary-Key Constraints Foreign-Key Constraints Modifying Constraints Adding Constraints Removing Constraints Information on Constraints: sp_helpconstraint ***********************Comparing Data-integrity Methods: Rules, Defaults, Indexes, Constraints, Keys (Primary Key, Foreign Key (pri mary key from another table), Common key)

T-SQL programming constructs

T-SQL programming constructs: standard arithmetic operations ( + - * / ^) string functions: datalength(), substring(), right(), upper(), lower(), space(), replicate(), stuff(), reverse(), ltrim(), rtrim(), ascii(), char(), str(), soundex(), difference(), charindex(), patindex() note: to include quotes into string you can repeat it 2 times (or one time if the surrounding quote is of different type):

" "" " ' '' ' " ' " ' " ' 'I don''t know'

"I don't know"

" Title ""The Title"" was on sale"

' Title "The Title" was on sale'

math.functions: abs(), ceiling(), exp(), floor(), pi(), power(), rand(), round(), sign(), sqrt() date functions: getdate(), datename(), datepart(), datediff(), dateadd()  convert - to convert data types: select "Advance = " + convert (char(12), advance) from titles (can also convert dates) system functions: host_id(), host_name(), suser_id(), suser_name(), user_id(), user_name(), user, show_role(), db_id(), db_name(), object_id(), object_name(), col_name(), col_length(), index_col(), valid_name(), data length(), tsequal() compute, compute by: allows to include both detail and summary info in a single result set isnull - function tells to treat null values as zero or something else. Batches: several commands followed by 'go' command Comments: /* */ or * Local variables: declare @variable_name datatype declare @myname varchar(30), @type int select @myname=12 go

note: name length is limited to 30 char (including @) Global variables - can not be defined by users. (examples: @@rowcount, @@error, @@trancount, @@transtate, ...) Message handling: print "this is a message" declare @msg varchar(30) select @msg = "Hello " + user_name() print @msg Error handling: raiserror 52345 'Row not found' if .. else: if (select ...) print "sometext" else print "some_other_text" while: while(select ...) begin update ...

continue break  end goto: metka: select ... ... goto metka waitfor: waitfor time "22:00:00" while 1<2 begin waitfor delay "00:00:30" exec sp_who end

return: to exit the batch set: set rowcount 100 set statistics time on set nocount on ... Cursors - allow custom processing for each row: declare leads_curs cursor for select cust_id, ets-sale from leads for read only go

open leads_curs while () begin .. end close leads_curs deallocate leads_curs go You can do also custom updating with cursors. In general you should avoid cursors - try to substitute them sith complex select statements (usually will run x10 faster)

Triggers

***************create trigger [owner.]trigger_name on [owner.]table_name {for {insert, update, delete} as SQL_statements Or, using the if update clause: create trigger [owner.]trigger_name on [owner.]table_name for {insert, update} as [if update (column_name ) [{and | or} update (column_name)]...] SQL_statements [if update (column_name) [{and | or} update (column_name )]... SQL_statement ] ... Example: create trigger titles_trigger on titles for insert as print "title inserted" return ***************drop trigger trigger_name ***************create trigger cascade_del_trigger on publishers for delete as if @@rowcount = 0 -- no rows deleted, exit trigger return delete titles from titles t, deleted d where t.pub_id = d.pub_id if @@error != 0 begin print "Error occurred during deleting related titles" end

return ***************create trigger tr1 on ... for insert, update as declare @rows int select @rows = @@rowcount ... if (.. ) ... ***************In triggers you CAN NOT do these: create, drop, alter table/database, grant, revoke, select into, tr uncate table, update statistics, reconfigure, load database/transaction, disk init/mirror/reinit/refit/remirror/unmirror ***************Triggers During transactions: ... begin tran add_titles insert ... insert ... commit tran ***************rollback trigger - command to rollback the trigger Nested Triggers - 16 levels of nesting max ,

Stored procedures Stored Procedures: * faster (precompiled in memory) * reduced network traffic * modular programming * restricted access to tables * reduced operator error * enforced consistency * automated complex or sensitive transactions ***************create proc pub_titles as select .. from ... where ... return To execute a stored procedure: call by name if it is a first command in the batch or use "exec" (or "execute" command): exec proc_name To delete the procedure: drop proc proc_name To change the procedure: if exists (select * from sysobjects where name = "titles_for_a_pub" and type = "P" and uid=user_id()) drop proc titles_for_a_pub go create proc titles_for_a_pub as ... To display the text of the procedure: sp_helptext proc_name passing parameters: create proc tt (@pub_name varchar(40)) as select ...where ... return

declare @my_pname varchar(40) select @my_pname ="Some text" exec tt @my_pname Default Parameter Values: create proc proc_name p_name datatype = default_value

, .... as SQL Statements return ... ----- Output parameters: create proc tt ( @par1 varchar(80) = null, @par2 int output) as -- some T-SQL statements go here return

declare @myoutput int exec tt @par1 = 'sometext', @par2 = @myoutput output go ----- Returning procedure status: return some_int_value 0 - no errors *1 .. -99 - detected errors (page 194 - list of error status codes) other values - whatever you like

declare @staatus_var int exec @staatus_var = proc_name Note: A stored procedure may NOT: create views, defaults, rules, triggers or proc edures, or issue the use statement Note: If stored procedure references a table, and the table was changed - you may have to drop procedure, change it and re-create it. When created, stored procedure is transformed into a cashed sequenced of SQL statements. If procedure has "with recompile" - it forces the optimizer to generate a new query plan for each execution. ----- Returning data from one SP into a caller-SP: --------------------------------------- transparent passing the result value ----------------------------------create proc test1 as select count(1) N from OE create proc test2 as exec test1 exec test2 --------------------------------------- catch the output value in the caller SP: ----------------------------------create proc test3(@a int, @b int output) as select @b = @a*@a

create proc test4 as begin declare @par_in int declare @par_out int declare @ret_status int select @par_in = 3 exec @ret_status = test3 @par_in, @par_out output if not @ret_status=0 begin select @par_out = 0 end select @par_out select @par_out+1 end exec test4 --------------------------------------- transparent passing the result set ----------------------------------create proc test5 as select * from mytab create proc test6 as exec test5 exec test6 --------------------------------------- handling errors, transactions -----------------------------------

create proc mysp as begin declare @tran_cnt int declare @errs int declare @rows int select @tran_cnt = @@trancount if @tran_cnt = 0 begin transaction mytran else save transaction mytran -- do something useful -- then check for errors select @errs = @@error if (@errs != 0) begin rollback transaction sbl_upd_ticker return @errs end select @loc=loc, @idx=idx from mytab if not @@rowcount=1 begin rollback transaction mytran raiserror 30200 return 30200 end if @tran_cnt = 0 commit transaction mytran select @my_id = (@loc * 10000000) + @idx return 0 end Objects referenced in a procedure: exec sp_depends proc_name exec sp_depends table_name

Transactions Transactions - several statements grouped together and either commited or rollbacked all together (all individual steps are recorded into a transaction log for recovery in case of a crash) begin tran save tran rollback tran commit tran set chained @@tranchained 0 - chained mode is off, 1 - chained mode is on

begin transaction update something insert something if ... begin ... commit transaction end else begin ... rollback transaction end Note: transactions put locks on pages (2K blocks of data) savepoints inside transaction: save tran item999

... rollback tran item999 Nested Transactions: @@trancount stored procedure with a t ransaction inside

create proc p1 as declare @trncnt int select @trncnt = @@trancount if @trncnt = 0 begin tran p1 else save tran p1

-- save value

 /* do some work here */  if (@@transtate = 2) -- or other error condition begin rollback tran p1 return 25 -- error code indicating rollback  end  /* some more processing if required */  if @trncnt = 0 commit tran p1 return 0 -- success nesting transactions - batch with transaction calls a stored procedure with a transaction inside

..... declare @status_val int, @trncnt int select @trncnt = @@trancount -- save value if @trncnt = 0 begin tran t1 else save tran t1  /* do some work here */  if (@@transtate = 2) -- or other error condition begin rollback tran t1 return -- exit batch end execute @status_val = p1 -- call procedure with transaction from inside transaction - thus nesting transactions if @status_val = 25 -- if proc p1 performed rollback  begin rollback tran t1 return end if @trncnt = 0 commit tran t1 -- decrements @@trancount to 0 return triggers may be part of a transaction:

begin tran update titles set price=$99 where title_id = "BU1234" commit tran rollback transaction in a trigger rollback trigger Transation modes:

- chained mode - This is ANSI standard. You are always in a transaction. You never have to issue BEGIN TRANs because it is issued implicitly as soon as you connect, and then as soon as you finish previous transaction. So as soon as you issue explicit COMMIT TRAN or ROLLBACK TRAN - you will get into a new transaction. It looks strange - you only close transactions with commit or rollback - and never have to open it, because it is always already opened for you. - unchained mode (default for Sybase) - Each individual statement is atomic. If you want to put several statements in one transactions - you have to explicitly issue BEGIN TRAN and at the end do COMMIT or ROLLBACK. Stored procedures remember in which mode they were compiled - and will not run in a different mode - unless you define them with "anymode".

Getting info from sys. tables

some examples using sys tables -------------------------------------------------------select name from sysobjects where sysstat & 7 = 3 order by name -------------------------------------------------------select rowcnt(t2.doampg), (reserved_pgs(t2.id, t2.doampg) + reserved_pgs(t2.id,t2.ioampg)), (t3.low), data_pgs(t2.id, t2.doampg), data_pgs(t2.id,t2.ioampg), ( (reserved_pgs(t2.id, t2.doampg) + reserved_pgs(t2.id,t2.ioampg)) (data_pgs(t2.id, t2.doampg) + data_pgs(t2.id,t2.ioampg)) ) from sysobjects t1, sysindexes t2, master.dbo.spt_values t3 where t2.id = object_id('myTableName') and t1.id = object_id('myTableName') and t3.number = 1 and t3.type = 'E' ------------------------------------------------------select t1.name, t2.name, t1.length, t1.status from syscolumns t1, systypes t2 where t1.id = object_id('my_name') and t1.usertype *= t2.usertype -------------------------------------------------------select t1.indid, t1.name from sysindexes t1 where t1.id = object_id('my_name') and t1.indid > 0 and t1.indid < 255 -------------------------------------------------------select index_col('my_name', indid_buf, keyid_buf, ...) -------------------------------------------------------select t1.name from master.dbo.spt_values t1, sysindexes t2 where t2.status & t1.number = t1.number and t2.id = object_id('my_name') and t2.indid = my_some_indid_buf  and t1.type = 'I' and t1.number = 2 -------------------------------------------------------select t1.name

from syssegments t1, sysindexes t2 where t1.segment = t2.segment and t2.id = object_id('my_name') and t2.indid = my_some_indid_buf  -------------------------------------------------------select replstat = convert(bit, (t1.sysstat & -32768)) from sysobjects t1 where t1.id = object_id('my_name') --------------------------------------------------------

Stored procedure with a cursor

if exists (select 1 from sysobjects where name = "myname") drop proc myname go create proc myname as begin declare @my_id int declare @root_my_id int declare mycursor cursor for (select my_id from MT) open mycursor fetch mycursor into @my_id while ((@@sqlstatus = 0)) begin exec @root_my_id = MT_get_root @my_id insert into MT_root_map_tmp (my_id, root_my_id) values (@my_id, @root_my_id) fetch mycursor into @my_id end close mycursor deallocate cursor mycursor end go

script to copy data between databases

You can copy data between databases using migrate utility in DBArtisan. Or you can use this script (it accepts table name as a parameter): #!/bin/sh -v if [ $# != 1 ] then echo "Usage: $0 " exit 1 fi table=$1 PROD="-S SERV1 -U user1 -P pass1" DEV="-S SERV2 -U user2 -P pass2" bcp mydb..$table out $table.dat $PROD -n > /dev/null isql $DEV -w250 <
go EOF bcp mydb..$table in $table.dat $DEV -n > /dev/null isql $DEV -w250 <
misc

count distinct types:

select dept, count(*) from mytable where dept is null group by dept union select distinct dept, count(*) from mytable where dept is not null group by dept

select distinct dept, count(isnull(dept,'0')) from mytable group by isnull(dept,'0')

when you joining tables - they join only on not null values.

example of a union:

The common situation is joining 2 tables through a middle table which maps keys between the side 2 tables. This works good for normal inner joins: select ... where A.x = B.x and B.y = C.y

select #t1.* from #t1,#t2 where #t1.bb = #t2.bb union But what if you want all values from A - and just fill with nulls other columns. You try left join - select t1.* but it doesn' work: from #t1 t1 select ... where A.x = B.x and B.y = C.y -- doesn't work where not exists ( select * from #t2 t2 You can either do it in 2 steps (make a temporary table) - or use union: where t1.bb = t2.bb ) Getting date difference as part of the year in Sybase

-- select convert(numeric(6,2), datediff(mm, '4/1/02', '1/1/03'))/12.00 -- select convert(numeric(6,2), datediff( dy, '4/1/02', '1/1/03' ))/365.00 -- select convert(numeric(6,2), datediff( dy, '4/1/02', '7/1/02' ))/365.00 Catching special characters:

select count(*) from mytab where charindex(char(10), myname) !=0 The simple way to find all occurencies of special characters is to use a short perl script. Below is the code (do_query is a self-made subroutine returning the result set as an array of hashes):

my ($sql,$result,$row,$oe_id,$name,@ar,%hh); $sql = qq{ select id, name from mytab where name like '%[^0-9A-Za-z -_.,''""%]%' }; $result = &do_query($dbh, $sql); for $row (@$result) { $id = $row->{id}; $name = $row->{name}; @ar = unpack('C*', $name); %hh = (); for(@ar) {if($_<32 or $_>127){$hh{$_}++}} for(sort keys %hh){print"id <$id>: code $_ - $hh{$_} times\n"} }

declare @a varchar(30) select @a = "a b" select @a = str_replace(@a, char(32), rtrim('')) select @a -- the above returns 'ab' in Sybase 12.5.1 and later, but returns NULL in 12.5.0, which is a bug -- The alternative is to use a while loop: declare @ss varchar(10) select @ss="a b" while (charindex(" ",@ss) > 0) select @ss = substring(@ss, 1, charindex(" ",@ss)-1) + substring(@ss, charindex(" ",@ss)+1, 255) select @ss =========================== Using 'union' to do logical operations in single statement without creating temporary tables: Let's say we have a table with 2 columns (a,b): create table #t (a int null, b int null) insert #t (a,b) values (-1,6) insert #t (a,b) values (0,5) insert #t (a,b) values (1,4) insert #t (a,b) values (2,3) insert #t (a,b) values (3,2) and we want to return max(a) or max(b) depending on which one is larger. Here is how this could be done

select max(b) mm from #t having max(b) > (select max(a) from #t) union select max(a) mm from #t having max(b) > (select max(b) from #t)

tune your SQL Query Tuning Options set forceplan on - forces SQL Server to join the tables in a query in the order in which they are listed in the from clause. set table count - allows you to specify the number of tables that are considered at once as joins are optimized. sp_cachestrategy - disables and reenables cache strategies and large I/O for individual objects. specify the index, cache strategy, or I/O size for a query (for example: select * from mytab (index mytab_idx) where ... ) set prefetch - allows you to enable or disable large I/O for a session.

Benchmarking your query by hand: set statistics time on set statistics IO on

Help your optimizer to make sure it has correct information about your table and uses it for queries and stored procedures. T his info may me incorrect, for example, after bulk loads: update statistics tabname sp_recompile tabname Examine the showplan of your query: set showplan on go set noexec on go or for a stored procedure set showplan on go set fmtonly on go

Note: do not mix set noexec & set fmtonly Run your code - examine the output - look where table scans are made instead of using indexes. Sometimes index is not used because: - it doesn't exist on the column used in the where clause or in a join - there is a datatype mismatch in the join (like integer joined to numeric) - if the query is not restrictive enough and returns significant portion of the table. The optimizer then will choose to use table scan. - the indexes are very complex - so Optimizer decides that it is less costly to just read the table itself  - some where cluases may cause problems: order by, group by, having, between, like, calculations in where clauses. - sometimes table scan is really more effective and you don't need to eliminate it. Note, that database can cashes data, so repeating the query may get the results faster. Simple solution - vary the query. dbcc traceon(302, 310, 3604) sp_sysmon etc.

Dynamic SQL

-- "dynamic SQL" in Sybase is called "execute-immediate" (EI) exec("select getdate()") declare @c varchar(25) select @c = "select getdate()" exec (@c) select @c = 'mycolumn' execute( 'select ' + @c + ' from mytable where 1=2' ) -- You can do line continuation like this: exec (' \  create procedure myproc \  @part1 int \  as \  select KeyCol, Attrib \  from MyTable \  where KeyCol = @par1 \  ') -- Note: -- temp tables (#mytemp) created inside are dropped on exit -- local variables created outside can not be used inside - and vice versa -- some commands are not allowed inside: use, set, dbcc, connect, begin transaction, commit, rollback, du mp transaction -- can't call EI from inside another EI, inside a trigger, -- statements executed in EI can't access tables "inserted" and "deleted" -- and EI doesn't return the result status -- cursor usage is limited (and pointless) -- Passing info back from EI - via table -- EI sets @@rowcount and @@error as any other SQL Real-life example (extracted from the middle of a long stored proc): declare @mysql varchar(1024) select @mysql = "insert #client1cas (id_cas) " select @mysql = @mysql + "select w.id_cas " select @mysql = @mysql + "from jds_words_cas w (index IX_words) " select @mysql = @mysql + "where w.words like '" + @client_str + "%' " select @mysql = @mysql + " and w.id_cas != null and w.id_cas != '' " set rowcount @max_mid_rows execute(@mysql) select @myrowcount = @@rowcount set rowcount 0 if (@mydebug = 1) print "________ inserted %1! rows", @myrowcount if(@rows_cas >= @max_mid_rows) begin select @many_clients_flag = 1 goto RETURN_RESULTS end

Getting Info About Rows and Sizes of Tables

select Table_Name=object_name(id), "Rows"=convert(int,sum(rowcnt(doampg))), "ReservedKB"=sum(reserved_pgs(id,doampg))*2+ sum(reserved_pgs(id,ioampg))*2, "Data"=sum(data_pgs(id,doampg))*2 , "Index"=sum(data_pgs(id,ioampg))*2 from sysindexes where id in (select id from sysobjects where type='U') group by object_name(id) Testing Outer Joins

When chaining joins, >> , =>, <> are OK, but >= is not allowed (even on a different key) -- testing outer joins create table #t1 (c1 varchar(10) null, c2 varchar(10) null) create table #t2 (c1 varchar(10) null, c2 varchar(10) null) create table #t3 (c1 varchar(10) null, c2 varchar(10) null) go -- row.col insert #t1 values('1.1','1.2') insert #t1 values('2.1','2.2') insert #t1 values('3.1','3.2') insert #t2 values('1.1','1.2') insert #t2 values('2.1','2.2') insert #t2 values('4.1','4.2') insert #t3 values('1.1','1.2') insert #t3 values('2.1','2.2') insert #t3 values('5.1','5.2') select t1.*, t2.* from #t1 t1, #t2 t2 where t1.c1 = t2.c1 select t1.*, t2.* from #t1 t1, #t2 t2 where t1.c1 *= t2.c1 -- t1 < t2 > t3 select t1.*, t2.*, t3.* from #t1 t1, #t2 t2, #t3 t3 where t1.c1 =* t2.c1 and t2.c1 *= t3.c1 -- t1 > t2 > t3 select t1.*, t2.*, t3.* from #t1 t1, #t2 t2, #t3 t3 where t1.c1 *= t2.c1 and t2.c1 *= t3.c1 -- t1 < t2 = t3 select t1.*, t2.*, t3.* from #t1 t1, #t2 t 2, #t3 t3 where t1.c1 =* t2.c1 and t2.c1 = t3.c1 -- t1 > t2 < t3 - meaningless select t1.*, t2.*, t3.* from #t1 t1, #t2 t2, #t3 t3 where t1.c1 *= t2.c1 and t2.c1 =* t3.c1 -- t1 > t2 = t3 - not allowed select t1.*, t2.*, t3.* from #t1 t1, #t2 t2, #t3 t3 where t1.c1 *= t2.c1 and t2.c1 = t3.c1 -- t1 > t2 = t3 - not allowed even on a different key select t1.*, t2.*, t3.* from #t1 t1, #t2 t2, #t3 t3 where t1.c1 *= t2.c1 and t2.c2 = t3.c2 print, raiserror =============================================== Example of using print with formatting string: =============================================== declare @a varchar(20) select @a = convert(varchar(20),getdate(),112) print @a

declare @b varchar(20) select @b = 'I am b' print @b

print "MYMY %1! and %2! MYMY", @a, @b =============================================== Few words about raiserror =============================================== raiserror is similar to print command, but it also sets the @@error global variable to a int nubmer. Sybase has its own errors with numbers <20000. (see their descriptions in table master..sysmessages) select count(1) from master..sysmessages select count(1) from master..sysusermessages You can create your own custom errors - either in sysusermessages - or on the fly Examples of usage if @@error != 0 begin raiserror 300004 , "some message" return -1 end raiserror 300002 , "MYMY %s MYMY ", @myvar raiserror 300002 , "MYMY %1! MYMY ", @myvar -- error 300006 doesn't exist in the sysusermessages table. -- so we call it without a comma after the error number and specify the message raiserror 300006 "MYMY %1! MYMY", @myvar Empty strings: select @country = isnull(rtrim(ltrim(@country)),"") note that empty chars are expanded inside the char_length() function. Thus char_length(""+"") = 2 A workaround this is to rtrim everything inside the char_length - and use isnull outside the char_length: isnull(rtrim(@nm_lst)),0) Note here that rtim("") returns null, so char_length(rtrim("")) is null also, and not zero. Isn't Sybase great, intuitive and easy to understand !!! Replacing in a string: select @nm_frst = str_replace(@nm_frst, "'", "''") Example of Printing: exec myprint @mydebug,63,"starting" if (@mydebug = 1) print "We limit the rowcount globally to %1! ro ws",@set_glob_rowcount create procedure myprint ( @myflag int = 1, -- 1 or 0 - to print or not @myline int = 0, -- the line number @mystring varchar(200) = "" -- the message string ) as begin ----------------------------------- usage -- myprint 1,57,"some message" -- or in stored proc: -- myprint @mydebug, 57,"some message" ----------------------------------

if (@myflag != 1) return declare @mydate varchar(30) select @mydate=convert(varchar(30),getdate(),109) print "%1! === line ~ %2! === %3!", @mydate, @myline, @mystring end Example of reporting a duration of some process: declare @mysec datetime select @mysec = getdate() -- do something if(@mydebug=1) begin select @ss = "FINISHED, total run time = " + convert(varchar(20),datediff(ss,@mysec,getdate())) + " seconds" exec myprint @mydebug,1012,@ss end Example populating a "suffix" table (chopping words from the beginning until nothing left). This table is used as an index ta ble to speed up search of words/phrases inside the string. It allows to use "starts with" logic ( ... where ss like 'xxx%' ), which uses index thus it is fast. CREATE PROCEDURE dbo.ins_words ( @words varchar(100) = null, @id varchar(32) = null, ) as BEGIN -- clean the @words select @words = upper(rtrim(ltrim(@words))) select @words = str_replace(@words, char(10), " ") -- \n select @words = str_replace(@words, char(9), " ") -- \t select @words = str_replace(@words, "|", " ") -- we do this to b e able to bcp select @words = str_replace(@words, "-", " ") -- dash is also a separator while (charindex(' ',@words)>0) select @words = str_replace(@words, " ", " ") -- remove double spaces -- we insert the whole string (even if it is empty - we still want to enter the id to make future updates easier) insert mytab (words, id) values (@words, @id_cas) if (rtrim(@words) = null) return declare @pos int select @pos = charindex(' ', @words) while (@pos > 0) -- have to insert substring(s) begin insert mytab (words,id) values (substring(@words,(@pos+1),200), @id) select @words = substring(@words,(@pos+1),200) select @pos = charindex(' ', @words) end END Update with variables technique: -- Example 1 declare @mycount int select @mycount=0 update jds_contact set @mycount = @mycount + 1 select @mycount -- We can do more interesting things - for example, concatenate values for the same id. let's say we have 2 columns (id, name). first, we create a temporary work table with 4 columns: (id, id_prev, name, names)

This table should have only fixed-width fields (no varchar). This is necessary so that the table will be written to the same place thus preserving th order of rows. Next we insert data into this table (order by id). Next we update the id_prev field: select @prev = 0 update #work set id_prev = @prev, @prev = id Next we do concatenation: select @ss="" update #work  set names = case when id != id_prev then rtrim(name) else rtrim(@names)+', '+rtrim(name) end, @ss = case when id != id_prev then rtrim(name) else rtrim(@names)+', '+rtrim(name) end Finaly select the result: select id, max(names) from #work  Example of batch inserting using id: declare @myrowcount int select @myrowcount=1 declare @min_id int, @max_id int, @base_id int select @min_id = min(id), @max_id = max(id) from source select @base_id = @min_id - 1 select * into #batch from dest where 1=2 set rowcount 5000 while (@myrowcount > 0) begin delete #batch insert #batch select * from source t where t.id > @base_id order by t.id select @myrowcount = @@rowcount select @base_id = max(id) from #batch if (@myrowcount > 0) begin insert dest select * from #batch print "inserted = %1! (max = %2!)", @base_id, @max_id end end set rowcount 0 Reducing the locking problem. Read - put shared lock, update or insert - exclusive lock. Table locks may be a result of lock promotion, but more often they happen because of your SQL / indexes. Normally table read puts a shared lock. But if you have an UPDATE or a DELETE with a WHERE clause which has a table scan - you will get an exclusive table lock without any lock pr omotion, regardless of locking scheme. Switching to row level locking (DATAROWS locking scheme) may not solve your problem and is very expensive: your data takes up more space, UPDATES start causing a lot more fragmentation, and you need A LOT more locks. Lock promotion works b y number of locks used, and since DATAROWS uses considerably more locks, you'll hit pr omotion threshold much sooner. Also if 

you run out of locks – you will also get a promotion to a table lock. Also, if you are committing more ro ws at a time than the HWM (high lock promotion threshold) – then you will still get lock promotion even with datarows locking scheme. There are 3 locking schemes: - ALLPAGES (data and indexes) - DATAPAGES (only data) - DATAROWS (only data, row-level locking) Use sp_lock and sp_objectstats to see if multiple connections/users attempt locks on ro ws on the same page. Use sp_sysmon to detect lock promotion. Lock promotion thresholds : LWM = 200 - never attempt a promotion below 200 locks HWM = 200 - always attempt promotion once 200 are reached (HLW - High WaterMark, LWM - Low WaterMark) Number of locks = 35,000 Note: Switching to DATAROWS might help your blocking, but maybe the problem isn't that people are trying to read the same row, or even different rows on the same page. It might be that they're blocking on data vs index access. DATAP AGES is a good first step to try since it eliminates index locking and usually this is all you need. It has most of the benefits of DATAROWS without the extreme overhead. It's always a good idea to try DATAPAGES first. Also, the solution to avoid table locks may be simply to increase the lock promotion thresholds. Note: changing from ALLPAGES to DATAPAGES or DATAROWS is a n expensive operation. Switching between DATAPAGES and DATAROWS is very easy and fast. Note: if a WHERE clause has local variables  – optimizer will not use index, t hus causing a table scan. Example:Modifying locking scheme: alter table authors lock datarows Isolation Level You can change isolation level using a command like this: set transaction isolation level 0

The value is stored in variable @@isolation Possible values: 0 - read uncommitted changes to data (allow dirty reads). 1 - read committed only (default) 2 - repeatable read - The transaction can repeat the same query, and no rows that have been read by the transaction will have been updated or deleted. 3 - serializable read - The transaction can repeat the same query, and receive exactly the same results. No rows can be inserted that would appear in the result set. You can override the isolation level by adding a hint to the end of SQL statement: with holdlock - force level 3 with noholdlock - force level 1

AutoCommit set autocommit - the client-side commant to set autocommit on | off | 0 | 1 - turns autocommit on or off. Duplicates ignore_dup_key - hint to skip duplicate keys while doing insert or update. Note - you cannot create a unique index on a column that includes duplicate values or more than one null value, whether or not ignore_dup_key is set. If you attempt to do so, Ad aptive Server prints an error message that displays the first of the duplicate values. You must eliminate duplicates before Adaptive Server can create a unique index on the column.

ignore_dup_row - allows you to create a new, nonunique clustered index on a table that includes duplicate rows. ignore_dup_row deletes the duplicate rows from the table , and cancels any insert or update that would create a duplicate row, but does not roll back the entire transaction.

Example: to delete duplicate rows: create index index_name on table_name with ignore_dup_row allow_dup_row - allows you to create a nonunique clustered index on a table that includes duplicate rows, and allows you to duplicate rows with update and insert statements.

tempdb, transaction log, You may have many databases on the same server. But until ver. 12.* there was only 1 tempdb database. This was creating problems, as many sessions were competing for it. Starting with ver. 12 you may have several database - thus distributing the load. Usuallythe size of tempdb is ~2 GBytes, however I've seen it as big as 12.5 GBytes - and completely buffered (mapped to memory). When you have large transactions - you may want to increase the sizes of both tempdb and transaction log. But if you have replication - you want to limit the size of transactions to ~ 3,000 rows. Checkpoint event Approximately once a minute, the checkpoint task checks each database on the server to see how many records have been added to the transaction log since the last checkpoint. If the server estimates that the time required to recover these transactions is greater than the database’s recovery interval, Adaptive Server issues a checkpoint. The modified pages are written from cache onto th e database devices, and the checkpoint even t is recorded in the transaction log. Then, the checkpoint task “sleeps” for another minute. To see the checkpoint task, execute sp_who. The checkpoint task is usually displayed as “CHECKPOINT SLEEP” in the “cmd” column. Working with big tables don't create a clustered index, because when you will need to drop and create it - ASE will lock the whole table. use range partitions to load data (starting with ver 15), and use local indexes (index on a partition) instead of global inde xes.

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