Question

Rather than have a NULL in a column, I want a 0 to be present.

Given the following two tables:

TABLE1
ClientID        OrderCount
1               NULL
2               NULL
3               NULL
4               NULL


Table2
ClientID        OrderCount
1               2
3               4
4               6

NOTE: The OrderCount column in both tables is INT datatype.

UPDATE TABLE1
SET OrderCount = ISNULL(TABLE2.OrderCount,0)
FROM TABLE1
INNER JOIN TABLE2 ON TABLE2.ClientID = TABLE1.CLIENTID

When I look at table1, I see this:

ClientID        OrderCount
1               2
2               NULL
3               4
4               6

So, I thought to myself – “Obviously, I should be using NULLIF and not ISNULL“, so I reversed them. Same result.

What am I doing wrong here? How do I get a 0 rather than a NULL in the column?

Answer 1

You need a LEFT JOIN rather than an INNER JOIN. The records that don’t have a matching ClientID are not even being touched by your query.