Normally
when you are querying data from two tables, you use a join. However, you can
also accomplish this with subqueries. One subquery technique is to use the IN
operator with the WHERE clause. You provide an inner query for the IN operator.
Then any rows in the outer table that match any one of the values in the IN
clause produce an output row.
Another
syntax to accomplish the same results as the IN operator is to use ANY. You add
this to the WHERE clause, using a comparison operator such as equals with ANY.
You pass the ANY a subquery to execute. If you are testing whether a column
equals this ANY expression, it behaves just like the IN scenario.
The benefit of using subqueries as described
above is that you can manually execute the SQL from the IN/ANY. Then you can
see the list of values you are trying to match with the outer table.
