what is exists in mysql?

EXISTS returns either true or false. The EXISTS is used to check for the existence of rows returned by the subquery. EXISTS operator returns TRUE if the subquery returns one or more rows. It can be used in a SELECT, INSERT, UPDATE, or DELETE statement.

Syntax -

SELECT column_name FROM table_name WHERE EXISTS (SELECT column_name FROM table_name WHERE condition);

With SELECT Statement

SELECT * FROM customers WHERE EXISTS (SELECT * FROM order_details WHERE customers.customer_id = order_details.customer_id);

ELECT name, occupation FROM customer WHERE EXISTS (SELECT * FROM Orders WHERE customer.customer_id = Orders.customer_id);

With SELECT Statement using NOT EXISTS

SELECT * FROM customers WHERE NOT EXISTS (SELECT * FROM order_details WHERE customers.customer_id = order_details.customer_id);

With INSERT Statement

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);

With DELETE Statement

DELETE FROM suppliers WHERE EXISTS (SELECT * FROM orders WHERE suppliers.supplier_id = orders.supplier_id);

Example

SELECT EXISTS(SELECT * from itechxpert WHERE emp_id=101) AS Result;

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