I ran across an issue with a subquery where I included a non-existent column.

select * from [Table1] where [ColumnA] in (

select [ColumnA] from [Table2] where [ColumnB] = true)

In this case, ColumnB didn’t belong to Table2. Running the subquery (select [ColumnA] from [Table2] where [ColumnB] = true) by itself would raise an error, since ColumnB isn’t in the table. But running the entire query returns an empty result set with no error raised.