Mysql 对数字的格式化

format函数：
     格式化浮点数 format(number, length);

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.

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‘

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.         

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.

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

Mysql 对数字的格式化

原文：http://www.cnblogs.com/duhuo/p/6250338.html