mysql中格式化数字详解

最近因为工作的需求，需要对mysql中数字进行格式化，但发现网上的资料较少，索性自己总结一下，方便自己也帮助有需要的朋友们，下面话不多说，来一起看看详细的介绍：

一、format函数：

格式化浮点数 format(number, length);

介绍：Formats the number X to a format like '#,###,###.##', rounded to D decimal places, and returns the result as a string. If D is 0, the result has no decimal point or fractional part. D should be a constant value.

示例代码

mysql> SELECT FORMAT(12332.123456, 4);
 -> '12,332.1235' 
mysql> SELECT FORMAT(12332.1,4);
 -> '12,332.1000' 
mysql> SELECT FORMAT(12332.2,0);
 -> '12,332'

二、rpad 和 lpad 给定位数，不足补充自定义字符

RPAD:

Returns the string str,right-padded with the string padstr to a length of len characters. If
str is longer than len, the return value is shortened to len characters.      

示例代码  

mysql> SELECT RPAD('hi',5,'?'); 
  -> 'hi???'
 mysql> SELECT RPAD('hi',1,'?'); 
  -> 'h'
mysql>SELET RPAD(12, 5 ,0);
  ->12000

This function is multi-byte safe.

LPAD:

Returns the string str, left-padded with the string padstr to a length of lencharacters. If str is longer than len, the return value is shortened to lencharacters.

示例代码

mysql> SELECT LPAD('hi',4,'??');
 -> '??hi' 
mysql> SELECT LPAD('hi',1,'??');
 -> 'h' 

mysql>SELECT LPAD(12, 5 , 0)
  ->'00012'

参考：http://www.cnblogs.com/fenglie/articles/4409208.html

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