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Editorial Team
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Asked: 2026-05-26T08:49:54+00:00

Here is the query which needs to be optimized: Scans: 527676 records… Returns: 496

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Here is the query which needs to be optimized:

Scans: 527676 records...
Returns: 496 records...

SELECT * FROM customers c
WHERE DATE_ADD(c.`custdate` ,INTERVAL -5 HOUR) BETWEEN '2011-09-14 00:00:00' AND '2011-09-14 23:59:59'
AND c.`custtype`='L'

This is the same without using DATE_ADD:

Scans: 801 records...
Returns: 481 records...

SELECT * FROM customers c
WHERE c.`custdate` BETWEEN '2011-09-14 00:00:00' AND '2011-09-14 23:59:59'

Question is how should I optimize this query using DATE_ADD() function? Without using DATE_ADD it picks up my indexes and query is fine.

Awaiting help on this.

Thanks,

Raheel

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1 Answer

  1. Editorial Team

    Since you’re just adding a constant time interval to c.custdate, what should work is instead to subtract that time interval from the BETWEEN values, to obtain a query that’s logically equivalent but permits MySQL to use the index. In general, if the query requires evaluation of a function of the index values, a range scan can’t be used.

    That is: instead of the WHERE clause being

    DATE_ADD(c.`custdate` ,INTERVAL -5 HOUR) BETWEEN '2011-09-14 00:00:00' AND '2011-09-14 23:59:59'

    make it

    c.`custdate` BETWEEN '2011-09-14 05:00:00' AND '2011-09-15 04:59:59'
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