Question

Let’s say that I have Table_A contain:

ID OldValue
3     16
1     5

and Table_B contains

ID Value OldValue
1    2     NULL
2    4     NULL 
3    8     NULL

and that I want to insert OldValues from Table_A into Table_B where the IDs equal resulting in :

updated Table_B

ID Value OldValue
1    2     5
2    4     NULL 
3    8     16

Is there a set based way of doing this without using a cursor? In real life this will be going on very large tables and cursors, as we all know are slow. Perhaps some sort of Merge?

I’m on SQL Server 2008

Answer 1

Update Table_B
Set OldValue = A.OldValue
From Table_A As A
    Join Table_B As B
        On B.ID = A.ID