Why does SQL Server thinks a Temp Table already exists when it doesn't?

Question

Background: There\'s a stored procedure which does \"stuff\" with a temp table of a given name. The procedure is generic in that it inspects the schema of the temp table and

Answer 1

It's a limitation. Dynamic SQL won't work either since #tmp will be created in a new session and immediately lost. For the EXACT snippet as shown, this does the same

CREATE TABLE #test
(
    a BIGINT NOT NULL,
    b BIGINT NOT NULL
)

IF not (1=1)
    ALTER TABLE #test ADD c BIGINT NOT NULL   

There cannot be two CREATE .. #name within the same batch, but this will also work in general form

IF (1=1)
BEGIN
    CREATE TABLE #test
    (
        a BIGINT NOT NULL,
        b BIGINT NOT NULL
    );
END 
GO

IF NOT (1=1)
BEGIN
    CREATE TABLE #test
    (
        a BIGINT NOT NULL,
        b BIGINT NOT NULL,
        c BIGINT NOT NULL   
    )
END