How Do You Check If A Temporary Table Exists In SQL Server

How do you check if a temp table exists?

You can use IF OBJECT_ID(’tempdb..#temp’) IS NOT NULL Let’s see how it works


–Create table
USE Norhtwind
GO

CREATE TABLE #temp(id INT)

–Check if it exists
IF OBJECT_ID(‘tempdb..#temp’) IS NOT NULL
BEGIN
PRINT ‘#temp exists!’
END
ELSE
BEGIN
PRINT ‘#temp does not exist!’
END

–Another way to check with an undocumented optional second parameter
IF OBJECT_ID(‘tempdb..#temp’,‘u’) IS NOT NULL
BEGIN
PRINT ‘#temp exists!’
END
ELSE
BEGIN
PRINT ‘#temp does not exist!’
END



–Don’t do this because this checks the local DB and will return does not exist
IF OBJECT_ID(‘tempdb..#temp’,‘local’) IS NOT NULL
BEGIN
PRINT ‘#temp exists!’
END
ELSE
BEGIN
PRINT ‘#temp does not exist!’
END


–unless you do something like this
USE tempdb
GO

–Now it exists again
IF OBJECT_ID(‘tempdb..#temp’,‘local’) IS NOT NULL
BEGIN
PRINT ‘#temp exists!’
END
ELSE
BEGIN
PRINT ‘#temp does not exist!’
END

–let’s go back to Norhtwind again
USE Norhtwind
GO


–Check if it exists
IF OBJECT_ID(‘tempdb..#temp’) IS NOT NULL
BEGIN
PRINT ‘#temp exists!’
END
ELSE
BEGIN
PRINT ‘#temp does not exist!’
END



now open a new window from Query Analyzer (CTRL + N) and run this code again

–Check if it exists
IF OBJECT_ID(‘tempdb..#temp’) IS NOT NULL
BEGIN
PRINT ‘#temp exists!’
END
ELSE
BEGIN
PRINT ‘#temp does not exist!’
END


It doesn’t exist and that is correct since it’s a local temp table not a global temp table

Well let’s test that statement

–create a global temp table
CREATE TABLE ##temp(id INT) –Notice the 2 pound signs, that’s how you create a global variable

–Check if it exists
IF OBJECT_ID(‘tempdb..##temp’) IS NOT NULL
BEGIN
PRINT ‘##temp exists!’
END
ELSE
BEGIN
PRINT ‘##temp does not exist!’
END

It exists, right?
Now run the same code in a new Query Analyzer window (CTRL + N)

–Check if it exists
IF OBJECT_ID(‘tempdb..##temp’) IS NOT NULL
BEGIN
PRINT ‘##temp exists!’
END
ELSE
BEGIN
PRINT ‘##temp does not exist!’
END

And yes this time it does exist since it’s a global table