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Editorial Team
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Asked: 2026-05-13T22:22:45+00:00

Given a database with two tables X and Y , I have a query

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Given a database with two tables X and Y, I have a query that should LEFT JOIN the two tables on attributes X.a1 and Y.b1. I used the following query:

SELECT X.a1, X.a2, Y.b1, Y.b2 FROM X LEFT JOIN Y ON (X.a1 = Y.b1)

I thought that would be good enough to work, even if Y is currently an empty table. However, the query breaks because table Y is empty, it seems. Is there any way to reformat this query so that even if Y is an empty table, the LEFT JOIN will not break? Or do I just need to always make sure that there is some data in table Y, even if it doesn’t match anything in table X (hence the LEFT JOIN).

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1 Answer

  1. Editorial Team

    Your table names are a little confusing. Is it X and Y, or X.a and Y.b?

    If X and Y:

    SELECT X.a1, X.a2, Y.a1, Y.b2 FROM X LEFT OUTER JOIN Y ON (X.a1 = Y.b1)

    should bring back all X, with nulls for the Y.a1 and Y.b2 where there is no matching record.

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