I have stumbled upon a quirk with lookup_ext which is causing me a bit of greif. I need to do a very complex lookup and hit a roadblock with the last column compare. In this column it is possible to have a null value or a real value and this is where lookup_ext fails to match the records. Here is the example which is a simplified version of what I am doing, ;
Transaction Table
| Record ID | Match_A | Match_B | Match_C |
|---|---|---|---|
| 1 | Gloves | Leather | Brown |
| 2 | Gloves | Driving | Brown |
| 3 | Gloves | Leather | NULL |
| 4 | Gloves | Driving | NULL |
| 5 | Gloves | NULL | Brown |
| 6 | Gloves | NULL | Black |
Look-up Table
| Match_A | Match_B | Match_C | Season | Stock_Ind |
|---|---|---|---|---|
| Gloves | Leather | Brown | Winter | Y |
| Gloves | Leather | Black | Winter | N |
| Gloves | Driving | Brown | Summer | N |
| Gloves | Driving | Black | Summer | Y |
| Gloves | Leather | NULL | Winter | Y |
| Gloves | Driving | NULL | Summer | Y |
| Gloves | NULL | Brown | Any Season | N |
| Gloves | NULL | Black | Any Season | N |
| NULL | Leather | Brown | Unknown | Y |
| ... and etc. |
I am using the Lookup_ext wizard as I have to return multiple columns, however when I run the routine it always fails to match where Null = Null. I am thinking that lookup_ext wants to only match Null when you specify Is Null but in this case i can't do that. Here is the output that the above tables in the Match Routine would give me.
| Record ID | Match_A | Match_B | Match_C | Season | Stock_Ind |
|---|---|---|---|---|---|
| 1 | Gloves | Leather | Brown | Winter | Y |
| 2 | Gloves | Driving | Brown | Summer | Y |
| 3 | Gloves | Leather | NULL | NULL | NULL |
| 4 | Gloves | Driving | NULL | NULL | NULL |
| 5 | Gloves | NULL | Brown | NULL | NULL |
| 6 | Gloves | NULL | Black | NULL | NULL |