关于Mysql计算出的数值和计算器算出的不一样怎么解决！
如上图这个sql 。cjPrice是600 cjNum是5.97 这种情况下
上面的sql算出的是3581.9998741149902 而计算器算出的是3582
而我用phpmyadmin执行如下sql 得到的也是3582 到底什么问题啊
select sum(600*5.97) 这也是3582
请问到底怎么解决啊~~~
回复讨论(解决方案)
如果你的 cjNum 不是 DECIMAL 类型的，那么应用 round 取结果
字段类型用的是 float 吧
单精度不准确
对精度要求高的话，建议换成double、decimal、numeric
double双精度，效率上差一点，但准确性高
decimal和numeric几乎等价，必须指定具体精度
你的查询结果是跟你那相乘的两个字段类型有关的
cjPrice整型 cjNum Float型
在phpmysql 下执行，是与mysql计算一样的，有小数位的。
估计和版本有关系吧，
可以试试 select round(SUM(cjPrice*cjNum), 2) from ..
保留两位小数
的确，我的cjPrice是decimal cjNum是float 我把 cjNum也改成decimal就行了
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