How does the IN predicate work in SQL?

Question

After prepairing an answer for this question I found I couldn\'t verify my answer.

In my first programming job I was told that a query within the IN ()

Answer 1

Most SQL engines nowadays will almost always create the same execution plan for LEFT JOIN, NOT IN and NOT EXISTS

I would say look at your execution plan and find out :-)

Also if you have NULL values for the Table1Id column you will not get any data back