I have the following query:
SELECT TOP 25 CLIENT_ID_MD5, COUNT(CLIENT_ID_MD5) TOTAL
FROM dbo.amazonlogs
GROUP BY CLIENT_ID_MD5
ORDER BY COUNT(*) DESC;
Which returns:
283fe255cbc25c804eb0c05f84ee5d52 864458
879100cf8aa8b993a8c53f0137a3a176 126122
06c181de7f35ee039fec84579e82883d 88719
69ffb6c6fd5f52de0d5535ce56286671 68863
703441aa63c0ac1f39fe9e4a4cc8239a 47434
3fd023e7b2047e78c6742e2fc5b66fce 45350
a8b72ca65ba2440e8e4028a832ec2160 39524
...
I want to retrieve the corresponding client name (FIRM) using the returned MD5 from this query, so a row might look like:
879100cf8aa8b993a8c53f0137a3a176 126122 Burger King
So I made this query:
SELECT a.CLIENT_ID_MD5, COUNT(a.CLIENT_ID_MD5) TOTAL, c.FIRM
FROM dbo.amazonlogs a
INNER JOIN dbo.customers c
ON c.CLIENT_ID_MD5 = a.CLIENT_ID_MD5
GROUP BY a.CLIENT_ID_MD5, c.FIRM
ORDER BY COUNT(*) DESC;
This returns something like:
879100cf8aa8b993a8c53f0137a3a176 126122 Burger King
06c181de7f35ee039fec84579e82883d 88719 McDonalds
703441aa63c0ac1f39fe9e4a4cc8239a 47434 Wendy's
3fd023e7b2047e78c6742e2fc5b66fce 45350 Tim Horton's
Which works, except I need to return an empty value for c.FIRM if there is no corresponding FIRM for a given MD5. For example:
879100cf8aa8b993a8c53f0137a3a176 126122 Burger King
06c181de7f35ee039fec84579e82883d 88719 McDonalds
69ffb6c6fd5f52de0d5535ce56286671 68863
703441aa63c0ac1f39fe9e4a4cc8239a 47434 Wendy's
3fd023e7b2047e78c6742e2fc5b66fce 45350 Tim Horton's
How should I modify the query to still return a row even if there is no corresponding c.FIRM?
Replace INNER JOIN
with LEFT JOIN