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Re[2]: [GENERAL] decimal_part() function

From: Sferacarta Software <sferac(at)bo(dot)nettuno(dot)it>
To: Herouth Maoz <herouth(at)oumail(dot)openu(dot)ac(dot)il>
Cc: pgsql-general(at)postgresql(dot)org
Subject: Re[2]: [GENERAL] decimal_part() function
Date: 1998-12-21 13:29:11
Message-ID: 11603.981221@bo.nettuno.it (view raw or flat)
Thread:
Lists: pgsql-general
Hello Herouth,

martedì, 15 dicembre 98, you wrote:

HM> At 17:46 +0200 on 15/12/98, Sferacarta Software wrote:


>> I'm looking for a function similar to dtrunc() to return the decimal
>> part of a float.
>>
>> dtrunc(12.34) returns 12, I need something that returns 34

HM> Here is a table having one float column named k. % is the truncation
HM> operator (I suppose it's the same as dtrunc). so... k - %k gives you only
HM> the fraction:

testing=>> select k, %k, k - %k from test1;
HM>     k|?column?|          ?column?
HM> -----+--------+------------------
HM>   1.8|       1|               0.8
HM>  3.78|       3|              0.78
HM>   0.4|       0|               0.4
HM>   1.8|       1|               0.8
HM>   0.4|       0|               0.4
HM>  9.24|       9|              0.24
HM>     6|       6|                 0
HM>  9.24|       9|              0.24
HM>   1.1|       1|               0.1
HM>  -1.8|      -1|              -0.8
HM> -10.2|     -10|-0.199999999999999
HM> (11 rows)

HM> If that's what you expect in the negative numbers, you're home free. If
HM> not, you can use some other operator combination.
HM> Herouth

I can't use this method because this has problems with precision, I
found this trick to have the decimal part with 3 decimal places...

prova=> select k, % k, k - %k, dround(date_part('millisecond',k)) from test;
      k|?column?|         ?column?|dround
-------+--------+-----------------+------
 123.45|     123|0.450000000000003|   450
123.101|     123|0.100999999999999|   101
 12.201|      12|0.201000000000001|   201
(3 rows)

Thanks any way.
-Jose'-



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