Example
The examples below fill in a PhoneNumber for any Employee who is also a Customer and currently does not have a phone number set in the Employees Table.
(These examples use the Employees and Customers tables from the Example Databases.)
Standard SQL
Update using a correlated subquery:
UPDATE
Employees
SET PhoneNumber =
(SELECT
c.PhoneNumber
FROM
Customers c
WHERE
c.FName = Employees.FName
AND c.LName = Employees.LName)
WHERE Employees.PhoneNumber IS NULL
SQL:2003
Update using MERGE:
MERGE INTO
Employees e
USING
Customers c
ON
e.FName = c.Fname
AND e.LName = c.LName
AND e.PhoneNumber IS NULL
WHEN MATCHED THEN
UPDATE
SET PhoneNumber = c.PhoneNumber
SQL Server
Update using INNER JOIN:
UPDATE
Employees
SET
PhoneNumber = c.PhoneNumber
FROM
Employees e
INNER JOIN Customers c
ON e.FName = c.FName
AND e.LName = c.LName
WHERE
PhoneNumber IS NULL
