How to do a full outer join of two tables with the same layout not repeating the?
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08-06-2021 - |
Question
I have to tables with the same layout (same columns). There is one ID and other data. I need a query that returns only one ID setting the data fields to null if that ID wasn't available at the required table.
Example:
Table A
ID - Val1 - Val2
1 - 2 - 2
2 - 3 - 3
4 - 1 - 5
Table B
ID - Val1 - Val2
2 - 3 - 3
3 - 2 - 1
4 - 2 - 3
Result
ID - Val1A - Val2A - Val1B - Val2B
1 - 2 - 2 - NULL - NULL
2 - 3 - 3 - 3 - 3
3 - NULL - NULL - 2 - 1
4 - 1 - 5 - 2 - 3
I'm using MS SQL Server. Thanks!
Solution
use coalesce to grab the non null id, the other columns will be null for the non matching table
select coalesce(a.id,b.id) as ID, Val1A , Val2A , Val1B , Val2B
from TableA a
Full outer join tableB b
ON <.....>
OTHER TIPS
SELECT COALESCE(a.ID,b.ID) AS ID,
a.Val1 AS TableA_Val1,
a.Val2 AS TableA_Val2,
b.Val1 AS TableB_Val1,
b.Val2 AS TableB_Val2
FROM TableA a
FULL OUTER JOIN TableB b
ON a.ID = b.ID
You can test it here: http://sqlfiddle.com/#!3/51b8c/3
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