Re: T-SQL problem - Perl solution?

[EdwardG]

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

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

[Win]

Should the following work?

WHILE (exists(select 1 from INFORMATION_SCHEMA.tables where table_name
+ = 'Experimental_parameters')

   ...

[monktim]

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.

[EdwardG]

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')

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

[EdwardG]

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?