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I see more and more people asking how to check if a temporary table exists. 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
I have also added this to our wiki, read it here: Check If Temporary Table Exists
