函数

在本文下面的表列出了 DQL 语句和 DML 语句对函数的支持情况。需要注意的是，在 DML 语句中使用函数，不能将其作为主键。

DML语句支持

类型是否支持
CONCAT(string2[,…])是
INSTR(string,substring)是
LCASE(string2)是
LEFT(string2,length)是
LENGTH(string)是
LOAD_FILE(file_name)是
LOCATE(substring,string[,start_position])是
LPAD(string2,length,pad)是
LTRIM(string2)是
REPEAT(string2,count)是
REPLACE(str,search_str,replace_str)是
RPAD(string2,length,pad)是
RTRIM(string2)是
STRCMP(string1,string2)是
SUBSTRING(str,position[,length])是
TRIM([[BOTH|LEADING|TRAILING][padding]FROM]string2)是
UCASE(string2)是
RIGHT(string2,length)是
SPACE(count)是
ABS(number2)是
BIN(decimal_number)是
CEILING(number2)是
CONV(number2,from_base,to_base)是
FLOOR(number2)是
FORMAT(number,decimal_places)是
HEX(DecimalNumber)是
LEAST(number,number2[,..])是
MOD(numerator,denominator)是
POWER(number,power)是
RAND([seed])是
ROUND(number[,decimals])是
SIGN(number2)是
SQRT(number2)是
ADDTIME(date2,time_interval)是
CONVERT_TZ(datetime2,fromTZ,toTZ)是
CURRENT_DATE()是
CURRENT_TIME()是
CURRENT_TIMESTAMP()是
DATE(datetime)是
DATE_ADD(date2,INTERVALd_valued_type)是
DATE_FORMAT(datetime,FormatCodes)是
DATE_SUB(date2,INTERVALd_valued_type)是
DATEDIFF(date1,date2)是
DAY(date)是
DAYNAME(date)是
DAYOFWEEK(date)是
DAYOFYEAR(date)是
EXTRACT(interval_nameFROMdate)是
MAKEDATE(year,day)是
MAKETIME(hour,minute,second)是
MONTHNAME(date)是
NOW()是
SEC_TO_TIME(seconds)是
STR_TO_DATE(string,format)是
TIMEDIFF(datetime1,datetime2)是
TIME_TO_SEC(time)是
WEEK(date_time[,start_of_week])是
YEAR(datetime)是
DAYOFMONTH(datetime)是
HOUR(datetime)是
LAST_DAY(date)是
MICROSECOND(datetime)是
MONTH(datetime)是
MINUTE(datetime)是
FIRST()否
LAST()否
MIN()否
MAX()否
AVG()否
SUM()否
COUNT()否

DQL语句支持

类型读未提交读已提交
CONCAT(string2[,…])是是
INSTR(string,substring)是是
LCASE(string2)是是
LEFT(string2,length)是是
LENGTH(string)是是
LOAD_FILE(file_name)是是
LOCATE(substring,string[,start_position])是是
LPAD(string2,length,pad)是是
LTRIM(string2)是是
REPEAT(string2,count)是是
REPLACE(str,search_str,replace_str)是是
RPAD(string2,length,pad)是是
RTRIM(string2)是是
STRCMP(string1,string2)是是
SUBSTRING(str,position[,length])是是
TRIM([[BOTH|LEADING|TRAILING][padding]FROM]string2)是是
UCASE(string2)是是
RIGHT(string2,length)是是
SPACE(count)是是
ABS(number2)是是
BIN(decimal_number)是是
CEILING(number2)是是
CONV(number2,from_base,to_base)是是
FLOOR(number2)是是
FORMAT(number,decimal_places)是是
HEX(DecimalNumber)是是
LEAST(number,number2[,..])是是
MOD(numerator,denominator)是是
POWER(number,power)是是
RAND([seed])是是
ROUND(number[,decimals])是是
SIGN(number2)是是
SQRT(number2)是是
ADDTIME(date2,time_interval)是是
CONVERT_TZ(datetime2,fromTZ,toTZ)是是
CURRENT_DATE()是是
CURRENT_TIME()是是
CURRENT_TIMESTAMP()是是
DATE(datetime)是是
DATE_ADD(date2,INTERVALd_valued_type)是是
DATE_FORMAT(datetime,FormatCodes)是是
DATE_SUB(date2,INTERVALd_valued_type)是是
DATEDIFF(date1,date2)是是
DAY(date)是是
DAYNAME(date)是是
DAYOFWEEK(date)是是
DAYOFYEAR(date)是是
EXTRACT(interval_nameFROMdate)是是
MAKEDATE(year,day)是是
MAKETIME(hour,minute,second)是是
MONTHNAME(date)是是
NOW()是是
SEC_TO_TIME(seconds)是是
STR_TO_DATE(string,format)是是
TIMEDIFF(datetime1,datetime2)是是
TIME_TO_SEC(time)是是
WEEK(date_time[,start_of_week])是是
YEAR(datetime)是是
DAYOFMONTH(datetime)是是
HOUR(datetime)是是
LAST_DAY(date)是是
MICROSECOND(datetime)是是
MONTH(datetime)是是
MINUTE(datetime)是是
FIRST()是否
LAST()是否
MIN()是否
MAX()是否
AVG()是否
SUM()是否
COUNT()是否