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Asked: 2026-05-10T17:56:40+00:00

I have a table that looks like that: The rows are sorted by CLNDR_DATE

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I have a table that looks like that:

alt text

The rows are sorted by CLNDR_DATE DESC.

I need to find a CLNDR_DATE that corresponds to the highlighted row, in other words:
Find the topmost group of rows WHERE EFFECTIVE_DATE IS NOT NULL, and return the CLNR_DATE of a last row of that group.

Normally I would open a cursor and cycle from top to bottom until I find a NULL in EFFECTIVE_DATE. Then I would know that the date I am looking for is CLNDR_DATE, obtained at the previous step.

However, I wonder if the same can be achieved with a single SQL?

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1 Answer

  1. Warning: Not a DBA by any means. 😉

    But, a quick, untested stab at it:

    SELECT min(CLNDR_DATE) FROM [TABLE] WHERE (EFFECTIVE_DATE IS NOT NULL)   AND (CLNDR_DATE > (     SELECT max(CLNDR_DATE) FROM [TABLE] WHERE EFFECTIVE_DATE IS NULL   ))

    Assuming you want the first CLNDR_DATE with EFFECTIVE_DATE after the last without.

    If you want the first with after the first without, change the subquery to use min() instead of max().

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