Mysql存储过程 字符类操作.docx

一.字符串类?CONCAT (string2? [,... ]) //连接字串INSTR (string ,substring ) //返回substring首次在string中出现的位置,不存在返回0LCASE (string2 ) //转换成小写LEFT (string2 ,length ) //从string2中的左边起取length个字符LENGTH (string ) //string长度LOAD_FILE (file_name ) //从文件读取内容LOCATE (substring , string? [,start_position ] ) 同INSTR,但可指定开始位置LPAD (string2 ,length ,pad ) //重复用pad加在string开头,直到字串长度为lengthLTRIM (string2 ) //去除前端空格REPEAT (string2 ,count ) //重复count次REPLACE (str ,search_str ,replace_str ) //在str中用replace_str替换search_strRPAD (string2 ,length ,pad) //在str后用pad补充,直到长度为lengthRTRIM (string2 ) //去除后端空格STRCMP (string1 ,string2 ) //逐字符比较两字串大小,SUBSTRING (str , position? [,length ]) //从str的position开始,取length个字符,?注：mysql中处理字符串时，默认第一个字符下标为1，即参数position必须大于等于1mysql select substring(’abcd’,0,2);+———————–+| substring(’abcd’,0,2) |+———————–+|?????????????????????? |+———————–+1 row in set (0.00 sec)mysql select substring(’abcd’,1,2);+———————–+| substring(’abcd’,1,2) |+———————–+| ab??????????????????? |+———————–+1 row in set (0.02 sec)TRIM([[BOTH|LEADING|TRAILING] [padding] FROM]string2) //去除指定位置的指定字符UCASE (string2 ) //转换成大写RIGHT(string2,length) //取string2最后length个字符SPACE(count) //生成count个空格?二.数学类ABS (number2 ) //绝对值BIN (decimal_number ) //十进制转二进制CEILING (number2 ) //向上取整CONV(number2,from_base,to_base) //进制转换FLOOR (number2 ) //向下取整FORMAT (number,decimal_places ) //保留小数位数HEX (DecimalNumber ) //转十六进制注：HEX()中可传入字符串，则返回其ASC-11码，如HEX(’DEF’)返回4142143也可以传入十进制整数，返回其十六进制编码，如HEX(25)返回19LEAST (number , number2? [,..]) //求最小值MOD (numerator ,denominator ) //求余POWER (number ,power ) //求指数RAND([seed]) //随机数ROUND (number? [,decimals ]) //四舍五入,decimals为小数位数]注：返回类型并非均为整数，如：(1)默认变为整形值mysql select round(1.23);+————-+| round(1.23) |+————-+|?????????? 1 |+————-+1 row in set (0.00 sec)mysql select round(1.56);+————-+| round(1.56) |+————-+|?????????? 2 |+————-+1 row in set (0.00 sec)(2)可以设定小数位数，返回浮点型数据mysql select round(1.567,2);+—————-+| round(1.567,2) |+—————-+|?????????? 1.57 |+—————-+1 row in set (0.00 sec)SIGN (number2 ) //返回符号,正负或0SQRT(