Cannot rename the column of a temp table

Ok, so the actual solution is:

EXEC tempdb.sys.sp_rename N'##BigTable.Nos', N'Numbers', N'COLUMN';

Since the #temp table (even a ##global temp table) lives in tempdb, you need to invoke sp_rename there.

But further questions to consider:

• Why on earth are you using a ##global temp table? You know this effectively limits concurrency to ONE, right? What do you think will happen when two users call this code at the same time? Probably you want to use a #local temp table here, or maybe avoid #temp tables altogether.

• Why do you have the need to change the column name halfway through the script? Either name it right in the first place, or keep referencing the old name. How is the script later on going to know you changed the name? For what purpose?