From: Alex Keda
Date: February 15 2013 5:35am
Subject: MySQL 5.1: incorrect arithmetic calculation
List-Archive: http://lists.mysql.com/mysql/228976
Message-Id: <511DC92D.8070708@lissyara.su>
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bkp0# mysql h5000_bill
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 1643184
Server version: 5.1.68-log FreeBSD port: mysql-server-5.1.68

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affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input 
statement.

mysql> set names utf8;
Query OK, 0 rows affected (0.00 sec)

mysql> SELECT * FROM `WorksCompliteAgregate` WHERE (`ContractID` = 10369 
AND `Month` = 497);
+----------+------------+-------+-----------+----------+--------+---------+--------+
| ID       | ContractID | Month | ServiceID | Comment  | Cost   | 
Discont | Amount |
+----------+------------+-------+-----------+----------+--------+---------+--------+
| 10551851 |      10369 |   497 |     10000 | ¹20440 |   1.67 | 0.10 
|    365 |
| 10551854 |      10369 |   497 |     20000 | ¹20441 | 150.00 | 1.00 
|      1 |
+----------+------------+-------+-----------+----------+--------+---------+--------+
2 rows in set (0.00 sec)

mysql> SELECT SUM(`Amount`*`Cost`*(1-`Discont`)) as `Summ` FROM 
`WorksCompliteAgregate` WHERE (`ContractID` = 10369 AND `Month` = 497);
+--------+
| Summ   |
+--------+
| 548.59 |
+--------+
1 row in set (0.00 sec)

mysql> SELECT SUM(`Amount`*`Cost`*(1-`Discont`)*100)/100 as `Summ` FROM 
`WorksCompliteAgregate` WHERE (`ContractID` = 10369 AND `Month` = 497);
+------------+
| Summ       |
+------------+
| 548.594985 |
+------------+
1 row in set (0.00 sec)

mysql> SELECT 365 * 1.67 * ( 1 - 0.10);
+--------------------------+
| 365 * 1.67 * ( 1 - 0.10) |
+--------------------------+
|                 548.5950 |
+--------------------------+
1 row in set (0.00 sec)

mysql>
===============

but, my desktop calculator gives the result 548.60