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Asked: 2026-06-15T09:14:40+00:00

I have two select statements. SELECT … UNION SELECT … If I run the

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I have two select statements.

SELECT ...

UNION

SELECT ...

If I run the first SELECT, the data comes back fine.

If I run the second SELECT, the data comes back fine.

If I run both at the same time using a UNION, the first row is always a NULL.

I don’t get it. Anyone know why this could be causing an issue?

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1 Answer

  1. Editorial Team

    There is a NULL row in your data. What is hapening is that the union is doing a sort, which is bringing the NULL up to the first row.

    If you want to eliminate the NULL value, use a where clause.

    If you want your query to be more efficient by not eliminating duplicates, using union all.

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