最忌在做ORACLE到MYSQL得迁移，以下我写了三个简单的MYSQL里面米有的函数。 供大家参考。
判断是否为时间？
DELIMITER $$ USE `ytt`$$ DROP FUNCTION IF EXISTS `is_date`$$ CREATE DEFINER=`root`@`localhost` FUNCTION `is_date`( f_in CHAR(19)) RETURNS TINYINT(4) BEGIN -- Created by david.yang 2012/8/9. IF UNIX_TIMESTAMP(f_in) = 0 THEN RETURN 0; ELSE RETURN 1; END IF; END$$ DELIMITER ; 判断是否为数字?
DELIMITER $$ USE `ytt`$$ DROP FUNCTION IF EXISTS `is_number`$$ CREATE DEFINER=`root`@`localhost` FUNCTION `is_number`( f_in VARCHAR(255)) RETURNS TINYINT(4) label1:BEGIN -- Created by david.yang 2012/8/9. DECLARE cnt INT UNSIGNED DEFAULT 0; DECLARE i INT UNSIGNED DEFAULT 1; DECLARE j INT UNSIGNED DEFAULT 0; SET cnt = LENGTH(f_in); loop1:WHILE i < cnt DO SET j = ASCII(SUBSTR(f_in,i,1)); IF j < 48 OR j > 57 THEN RETURN 0; LEAVE label1; END IF; SET i = i + 1; END WHILE loop1; RETURN 1; END$$ DELIMITER ; ORACLE to_date 函数的MYSQL实现。
DELIMITER $$ USE `ytt`$$ DROP FUNCTION IF EXISTS `to_date`$$ CREATE DEFINER=`root`@`localhost` FUNCTION `to_date`( f_date VARCHAR(30), f_format VARCHAR(30) ) RETURNS VARCHAR(30) CHARSET utf8 BEGIN -- '20-08-2011 22:55:02', 'dd-mm-yyyy hh24:mi:ss' -- '02-11-2011', 'dd-mm-yyyy' -- Created by david.yang 2012/8/9. DECLARE i_year CHAR(4); DECLARE i_month CHAR(2); DECLARE i_day CHAR(2); DECLARE i_time CHAR(8); SET i_year = SUBSTR(f_date,7,4); SET i_month = SUBSTR(f_date,4,2); SET i_day = LEFT(f_date,2); IF LENGTH(f_date) = 10 THEN SET i_time = ''; ELSE SET i_time = RIGHT(f_date,8); END IF; RETURN CONCAT(i_year,'-',i_month,'-',i_day,' ',i_time); END$$ DELIMITER ;