Function To Check The Existence Of A Temp Table

This function, F_TEMP_TABLE_EXISTS, checks for the existence of a temp table (## name or # name), and returns a 1 if it exists, and returns a 0 if it doesn't exist.

The script creates the function and tests it. The expected test results are also included.

This was tested with SQL 2000 only.



if objectproperty(object_id('dbo.F_TEMP_TABLE_EXISTS'),'IsScalarFunction') = 1
begin drop function dbo.F_TEMP_TABLE_EXISTS end
go
create function dbo.F_TEMP_TABLE_EXISTS
( @temp_table_name sysname )
returns int
as
/*
Function: F_TEMP_TABLE_EXISTS

Checks for the existence of a temp table
(## name or # name), and returns a 1 if
it exists, and returns a 0 if it doesn't exist.

*/
begin

if exists (
select *
from
tempdb.dbo.sysobjects o
where
o.xtype in ('U')and
o.id = object_id( N'tempdb..'+@temp_table_name )
)
begin return 1 end

return 0

end
go
print 'Create temp tables for testing'
create table #temp (x int)
go
create table ##temp2 (x int)
go
print 'Test if temp tables exist'

select
[Table Exists] = dbo.F_TEMP_TABLE_EXISTS ( NM ),
[Table Name] = NM
from
(
select nm = '#temp' union all
select nm = '##temp2' union all
select nm = '##temp' union all
select nm = '#temp2'
) a


print 'Check if table #temp exists'

if dbo.F_TEMP_TABLE_EXISTS ( '#temp' ) = 1
print '#temp exists'
else
print '#temp does not exist'


print 'Check if table ##temp4 exists'
if dbo.F_TEMP_TABLE_EXISTS ( '##temp4' ) = 1
print '##temp4 exists'
else
print '##temp4 does not exist'
go

-- Drop temp tables used for testing,
-- after using function F_TEMP_TABLE_EXISTS
-- to check if they exist.

if dbo.F_TEMP_TABLE_EXISTS ( '#temp' ) = 1
begin
print 'drop table #temp'
drop table #temp
end

if dbo.F_TEMP_TABLE_EXISTS ( '##temp2' ) = 1
begin
print 'drop table ##temp2'
drop table ##temp2
end


Test Results:

Create temp tables for testing
Test if temp tables exist
Table Exists Table Name
------------ ----------
1 #temp
1 ##temp2
0 ##temp
0 #temp2

(4 row(s) affected)

Check if table #temp exists
#temp exists
Check if table ##temp4 exists
##temp4 does not exist
drop table #temp
drop table ##temp2



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