Re: T-SQL problem - Perl solution?

The object_id() function is still available in SQL 2000 and still returns NULL if you supply the name of a non-existent table - try this example -

use pubs
go
if object_id('jobs') is not null
    print 'jobs table exists'
else
    print 'jobs table does not exist'
go

---
jobs table exists
[download]

A better way would be to query the database schema, rather than abuse the object_id() function. Something like this:

use pubs
go
if exists(select 1 from information_schema.tables where table_name = '
+jobs')
    print 'jobs table exists'
else
    print 'jobs table does not exist'
go
[download]

Comment on Re: T-SQL problem - Perl solution? Select or Download Code

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Re^2: T-SQL problem - Perl solution? by Win (Novice) on Oct 25, 2004 at 13:52 UTC
Should the following work? `WHILE (exists(select 1 from INFORMATION_SCHEMA.tables where table_name + = 'Experimental_parameters') ...` [download]	[reply] [d/l]
Re^3: T-SQL problem - Perl solution? by monktim (Friar) on Oct 25, 2004 at 14:17 UTC
That should work Win. What's nice about using information_schema is that it's ANSI standard so it will work on compliant dBs. Your question pertains directly to T-SQL but I like to code generically when there isn't a performance hit. When I work on other dBs I have to remember less vendor specific stuff. You don't need the `SELECT 1` here. `SELECT *` with an `EXISTS` can yield internal performance optimizations with MS SQL Server. In this case it's probably trival but I thought I'd mention it.	[reply] [d/l] [select]
Re^4: T-SQL problem - Perl solution? by EdwardG (Vicar) on Oct 25, 2004 at 14:57 UTC
In this case SQL 2000 produces the exact same execution plan for "SELECT 1" and "SELECT " - D:\>copy con: select1.sql set showplan_text on go if exists (select 1 from sysobjects where xtype = 'U' and name = 'jobs +') print 'exists' else print 'doesn''t exist' ^Z 1 file(s) copied. D:\>copy con: selectstar.sql set showplan_text on go if exists (select from sysobjects where xtype = 'U' and name = 'jobs +') print 'exists' else print 'doesn''t exist' ^Z 1 file(s) copied. D:\>osql -dpubs -n -i selectstar.sql > selectstar.txt D:\>osql -dpubs -n -i select1.sql > select1.txt D:\>diff select1.txt selectstar.txt 3c3 < if exists (select 1 from sysobjects where xtype = 'U' and name = 'j +obs') --- > if exists (select * from sysobjects where xtype = 'U' and name = 'j +obs') [download] And while Win's SQL does compile without error, it may be a disaster in production. For example, this code (including the code you sanction) starts an infinite loop - `use pubs go create table Experimental_parameters (c char (1) primary key) insert into Experimental_parameters (c) values ('a') go create table another_table (c char (1) references Experimental_paramet +ers (c)) insert into another_table (c) values ('a') go WHILE (exists(select 1 from INFORMATION_SCHEMA.tables where table_name + = 'Experimental_parameters')) begin drop table Experimental_parameters -- fails end go print 'finished' -- never gets here` [download]	[reply] [d/l] [select]
Re^5: T-SQL problem - Perl solution? by monktim (Friar) on Oct 25, 2004 at 15:36 UTC
Re^3: T-SQL problem - Perl solution? by EdwardG (Vicar) on Oct 25, 2004 at 13:59 UTC
That's a hard question to give a meaningful answer to; it could work in a limited set of circumstances, but I don't know your intention, or your schema for that matter. For instance, is Experimental_parameters a temporary table?	[reply]