Question

I’ve two table:
Table A
ID Field1 ….

Table B
ID Field2 Field3 …

I would like to LOOP through table B and if a a record with same ID exits in table A, add the value Field2 and Field3 in Table A.

I don’t know how to do in T-SQL!

Answer 1

Using a loop construction is not necessary for this update, you can solve it in a neater way by using set operations. If I understand the question correctly you want to UPDATE table A with the values from table B. Use a query like this:

UPDATE TableA
  SET TableA.Field2 = TableB.Field2, TableA.Field3 = TableB.Field3
  FROM TableB
  WHERE TableA.ID = TableB.ID

You might wanna do an extra check in this query to see what the values in field 2 and 3 in table A are before replacing them.

(To test first what the results of this query will be, build a SELECT query from the UPDATE query above!)