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Asked: 2026-05-23T10:15:46+00:00

The round function sometime doesn’t work very well. I have in my db a

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The round function sometime doesn’t work very well. I have in my db a row like this:

field_1= 375
field_2= 0.65
field_3= 0.1 
field_4= 11

So we know that: field_1*field_2*field_3*field_4 = 268.125 so if I round it to 2 decimals -> 268.13.

But in mysql I got 268.12 -> Select round(field_1*field_2*field_3*field_4) from my table -> 268.12

This situation just happens with these values, I tried with other numbers and no problem the round works.

Any workaround about it. I tried in mysql 4.1.22, and 5.1.44 and I get the same issue. I read in other forum http://bugs.mysql.com/bug.php?id=6251 that it is not a bug, they said that it depends on the C library implementation.

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1 Answer

  1. Editorial Team

    What data type are you using for those columns?

    If you want exact precision then you should use NUMERIC or DECIMAL, not FLOAT, REAL, or DOUBLE.

    From the manual:

    The DECIMAL and NUMERIC types store exact numeric data values. 
These types are used when it is important to preserve exact precision, 
for example with monetary data.
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