The EXISTS condition is an operator whose right operand is a subquery. The result of an EXISTS condition is true if the subquery resolves to at least one row. The result of a NOT EXISTS condition is ...

Normalized data giving you problems? Learn how to use the SQL subselect statement and handle your database like a pro! Do you ever find yourself juggling queries to get the information you need?

The beauty and joy of a relational database is the concept of relational closure—everything is a table. Beyond the eponymous table, query results are also “tables.” Any query serves as a table to be ...