mysql逗号分隔函数_mysql split 函数(用逗号分隔)的实现
1:定義存儲過程,用于分隔字符串
DELIMITER $$
USE `mess`$$
DROP PROCEDURE IF EXISTS `splitString`$$
CREATE DEFINER=`root`@`%` PROCEDURE `splitString`(IN f_string VARCHAR(1000),IN f_delimiter VARCHAR(5))
BEGIN
DECLARE cnt INT DEFAULT 0;
DECLARE i INT DEFAULT 0;
SET cnt = func_get_splitStringTotal(f_string,f_delimiter);
DROP TABLE IF EXISTS `tmp_split`;
CREATE TEMPORARY TABLE `tmp_split` (`val_` VARCHAR(128) NOT NULL) DEFAULT CHARSET=utf8;
WHILE i < cnt
DO
SET i = i + 1;
INSERT INTO tmp_split(`val_`) VALUES (func_splitString(f_string,f_delimiter,i));
END WHILE;
END$$
DELIMITER ;
2:實現func_get_splitStringTotal函數:該函數用于計算分隔之后的長度,這里需要了解的函數:
REPLACE(str,from_str,to_str)
Returns the string str with all occurrences of the string from_str replaced by the string to_str. REPLACE() performs a case-sensitive match when searching for from_str.
例如:
mysql> SELECT REPLACE('www.mysql.com', 'w', 'Ww');
-> 'WwWwWw.mysql.com'
具體實現:
DELIMITER $$
USE `mess`$$
DROP FUNCTION IF EXISTS `func_get_splitStringTotal`$$
CREATE DEFINER=`root`@`%` FUNCTION `func_get_splitStringTotal`(
f_string VARCHAR(10000),f_delimiter VARCHAR(50)
) RETURNS INT(11)
BEGIN
RETURN 1+(LENGTH(f_string) - LENGTH(REPLACE(f_string,f_delimiter,'')));
END$$
DELIMITER ;
3:實現func_splitString函數:用于獲取分隔之后每次循環的值,這里需要了解的函數:
(1)REVERSE(str)
Returns the string str with the order of the characters reversed.
例如:mysql> SELECT REVERSE('abc');
-> 'cba'
(2)
SUBSTRING_INDEX(str,delim,count)
Returns the substring from string str before count occurrences of the delimiter delim. If count is positive, everything to the left of the final delimiter (counting from the left) is returned. If count is negative, everything to the right of the final delimiter (counting from the right) is returned. SUBSTRING_INDEX() performs a case-sensitive match when searching for delim.
例如:
mysql> SELECT SUBSTRING_INDEX('www.mysql.com', '.', 2);
-> 'www.mysql'
mysql> SELECT SUBSTRING_INDEX('www.mysql.com', '.', -2);
-> 'mysql.com'
具體實現:
DELIMITER $$
USE `mess`$$
DROP FUNCTION IF EXISTS `func_splitString`$$
CREATE DEFINER=`root`@`%` FUNCTION `func_splitString`( f_string VARCHAR(1000),f_delimiter VARCHAR(5),f_order INT) RETURNS VARCHAR(255) CHARSET utf8
BEGIN
DECLARE result VARCHAR(255) DEFAULT '';
SET result = REVERSE(SUBSTRING_INDEX(REVERSE(SUBSTRING_INDEX(f_string,f_delimiter,f_order)),f_delimiter,1));
RETURN result;
END$$
DELIMITER ;
使用:
(1)調用存儲過程:
CALL splitString('1,3,5,7,9',',');
(2):查看臨時表
SELECT val_ FROM tmp_split AS t1;
結果:
總結
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