How to check existence of a table from a different sql db?

Question

I have db A and db B. At the beginning of a stored procedure I want to back up all rows from B.mytable to B.mytablebackup. The rest of the stored procedure runs against tables on db A (which gathers data and writes it to B.mytable).

So I check to see if B.mytablebackup exists

IF EXISTS(SELECT 1 FROM B.dbo.mytablebackup)

and if it does, the stored procedure does an

INSERT INTO B..mytablebackup SELECT * FROM B..mytable

If it doesn't exist it does a

SELECT * INTO B..mytablebackup from B..mytable

But when I execute the stored procedure I get the error

There is already an object named 'mytablebackup' in the database

I added a Print statement and execution is taking the "does not exist" branch of the IF.

What am I doing wrong?

Solution 1

For SQL Server, you should use system view sys.tables to check if table exists.

IF EXISTS(SELECT 1 FROM B.sys.tables WHERE name = 'mytablebackup')

Solution 2

OBJECT_ID can be used too:

IF OBJECT_ID('B.dbo.mytablebackup') IS NOT NULL