Question

I am trying to pull records from two tables, a master table, and a transaction table.

My Master table contains all of my account IDs. My transaction table has any transaction run by these accounts with 3 columns: activity date, income, and charge type.

In the transaction table, some of these accounts may not appear at all because they have not performed a transaction during a given date range. However, I still need these accounts to appear on my result list when I query them.

So my data would look like this:

     Master Table:                         Transaction Table:

    | AccountID  |              | AccountID | ChargeType | ActivityDate| Income |
    --------------              -------------------------------------------------
    |      1     |              |     2     |    2000    |  8/31/2012  | $99.00 |
    |      2     |              |     3     |    2000    |  7/31/2012  | $79.00 |
    |      3     |              |     5     |    2000    |  9/30/2012  | $79.00 |
    |      4     |
    |      5     |

My query currently looks like:

select
    a.AccountID,
    b.ChargeType,
    b.ActivityDate,
    b.Income
From
    MasterTable as A
left join
    TransactionTable as B on a.AccountID = b.AccountID
where
    a.AccountID in ('1','2','3','4','5')
    and
    b.ActivityDate between '5/1/2012' and '11/30/2012'

From what I understand, this query should list all 5 accounts I’ve chosen, and display NULL values for the accounts not found in the TransactionTable.

Results I expect:

        | AccountID | ChargeType | ActivityDate| Income |
        -------------------------------------------------
        |     1     |    NULL    |     NULL    |  NULL  |
        |     2     |    2000    |  8/31/2012  | $99.00 |
        |     3     |    2000    |  7/31/2012  | $79.00 |
        |     4     |    NULL    |     NULL    |  NULL  | 
        |     5     |    2000    |  9/30/2012  | $79.00 |

The incorrect results I receive instead:

         | AccountID | ChargeType | ActivityDate| Income |
         -------------------------------------------------
         |     2     |    2000    |  8/31/2012  | $99.00 |
         |     3     |    2000    |  7/31/2012  | $79.00 |
         |     5     |    2000    |  9/30/2012  | $79.00 |

I assume I am misunderstanding something fundamental here. Any help is greatly appreciated!

Thanks in advance!

Answer 1

The reason is that you have the “b” table referenced in the where clause, so NULL values are filtered out.

Move the condition to the on clause:

From
    MasterTable A left join
    TransactionTable B
    on a.AccountID=b.AccountID and
       a.AccountID in ('1','2','3','4','5') and
       b.ActivityDate between '5/1/2012' and '11/30/2012'