The AND operator joins two or more conditions and returns results only when all the conditions are true. For example, the following query finds only the rows in which the contact's last name is Purcell and the contact's first name is Beth.

SELECT *
   FROM Contacts
   WHERE GivenName = 'Beth'
      AND Surname = 'Purcell';

The OR operator connects two or more conditions and returns results when any of the conditions is true. The following query searches for rows containing variants of Elizabeth in the GivenName column.

SELECT *
   FROM Contacts
   WHERE GivenName = 'Beth'
      OR GivenName = 'Liz';

The NOT operator negates the expression that follows it. The following query lists all the contacts who do not live in California:

SELECT *
   FROM Contacts
   WHERE NOT State = 'CA';