在mysqli中处理小数 [英] Handle decimal numbers in mysqli

问题描述

我必须将某些项目的价格放入mysql表中.创建表时，我使用的是DECIMAL(10,2)，因为我不需要在逗号后加上两位以上的数字(例如:123,45将被接受为输入，但是123,456将被四舍五入为123,45).

I have to put the price of some items inside a mysql table. When creating the table I'm using DECIMAL(10,2) as I don't need more than 2 digits after the comma (for example: 123,45 would be accepted as an input but 123,456 would be rounded to 123,45 with PHP).

第一个问题:使用DECIMAL(10,2)，我如何知道逗号前可以存储多少个数字?我知道它不是10，因为10只是Mysql在对这些数字进行数学运算时使用的精度:那么数字本身的长度在哪里指定?

First question: using DECIMAL(10,2), how do I know how many numbers may be stored before the comma? I know it is not 10, as 10 is just the precision Mysql uses when doing math with those numbers: so where the length of the number itself is specified?

第二个问题:我正在使用PHP对用户输入进行四舍五入以适应数据类型(逗号后以2个数字浮点).我应该如何使用mysqli->bind_param插入这些数据?我应该使用(c3>接受的以下哪种数据类型(来自文档)并可能:为什么)?

Second question: I'm using PHP to round user input to fit the data type (float with 2 numbers after the comma). How should I use mysqli->bind_param to insert those data? Which of these datatypes (from the documentation) accepted by bind_param should I use (and possibly: why)?

Character   Description
i   corresponding variable has type integer
d   corresponding variable has type double
s   corresponding variable has type string
b   corresponding variable is a blob and will be sent in packets

推荐答案

DECIMAL(10,2)表示10是要使用的最大位数. 2指定小数点右边有两个.因此，这意味着左侧还有8个数字.参见手册

DECIMAL(10,2) means that 10 is the maximum number of digits to be used. The 2 specifies that there are two on the right side of the decimal. So this means there are 8 digits left on the left side. See the manual

对于数据类型，应使用double，因为这是十进制数字.

As for the datatype, you should use double as this is for decimal numbers.

Integer没有小数点字符，因此它将限制所有数字. String用于文本而不是数字值. Blob用于二进制大对象EG:图像

Integer has no decimal chars, so it will floor all numbers. String is for text and not numeric values. Blob is for a binary large object, EG: an image

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