The SQL Server (Transact-SQL) EXISTS condition is used in combination with a subquery and is considered to be met if the subquery returns at least one row. It can be used in a SELECT, INSERT, UPDATE, or DELETE statement.
- SELECT * FROM employees WHERE EXISTS (SELECT * FROM contacts WHERE employees.last_name = contacts.last_name AND employees.first_name = contacts.first_name);
Example: with Insert Statement
The following is an example of an INSERT that uses the EXISTS condition:
- INSERT INTO contacts (contact_id, contact_name) SELECT supplier_id, supplier_name FROM suppliers WHERE EXISTS (SELECT * FROM orders WHERE suppliers.supplier_id = orders.supplier_id);
The following exp_update
- UPDATE suppliers SET supplier_name = (SELECT customers.name FROM customer WHERE customers.customer_id = suppliers.supplier_id) WHERE EXISTS (SELECT customers.name FROM customers WHERE customers.customer_id = suppliers.supplier_id);