Question

I am trying to come up with a query in MS Acess to compare two tables. I am basing my comparison on 4 fields postal_code, city, state and country.
I want to be able to get all records in table1 that do not have a match in table2.

Here is my sample data. I am expecting 2 records in the query output, that I have marked with a “*”

table1
======

POSTAL_CODE CITY        STATE_PROV  COUNTRY_CODE
*12345      Union       NJ          US
45678       Hillside    NJ          US
*45678      Union       NJ          US



table2
======

POSTAL_CODE     CITY        STATE_PROV  COUNTRY_CODE
45678           Hillside    NJ          US

Here is what I have tried, but does not do the job:

SELECT DISTINCT table1.*
FROM table1 LEFT JOIN table2 ON table1.POSTAL_CODE=table2.POSTAL_CODE
WHERE ((table2.POSTAL_CODE Is Null));

How do I accomplish this? Please let me know any suggestion.

Thank you.

Answer 1

The ON expression for the LEFT JOIN should include all 4 of those fields you want to match. I also left out DISTINCT.

SELECT
    t1.POSTAL_CODE,
    t1.CITY,
    t1.STATE_PROV,
    t1.COUNTRY_CODE
FROM
    table1 AS t1
    LEFT JOIN table2 AS t2
    ON
            t1.POSTAL_CODE = t2.POSTAL_CODE
        AND t1.CITY = t2.CITY
        AND t1.STATE_PROV = t2.STATE_PROV
        AND t1.COUNTRY_CODE = t2.COUNTRY_CODE
WHERE t2.POSTAL_CODE Is Null;