Use the UPDATE statement in SQL to update the values of a table row. Update lets you update the fields of a specific row or all rows in the table. The UPDATE statement has the following syntax:
UPDATE table_name SET column_name1=value1, ... , column_nameN=valueN [ WHERE search_condition ]
You should not attempt to update a record's primary key field. Your database typically enforces this restriction.
The UPDATE statement uses the optional WHERE clause, much like the SELECT statement, to determine which table rows to modify. The following UPDATE statement updates the e-mail address of John Smith:
UPDATE employees SET Email='jsmith@mycompany.com' WHERE EmpID = 51
Be careful using UPDATE. If you omit the WHERE clause to execute the following statement:
UPDATE employees SET Email = 'jsmith@mycompany.com'
you update the Email field for all rows in the table.