How can I do an UPDATE statement with JOIN in SQL Server?

Question

I need to update this table in SQL Server with data from its \'parent\' table, see below:

Table: sale

id (int)
udid         


        

Answer 1

A standard SQL approach would be

UPDATE ud
SET assid = (SELECT assid FROM sale s WHERE ud.id=s.id)

On SQL Server you can use a join

UPDATE ud
SET assid = s.assid
FROM ud u
JOIN sale s ON u.id=s.id