如何在SQL表列上进行拆分 [英] how to do a split on a sql table column
本文介绍了如何在SQL表列上进行拆分的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
我有一个表,其中存储了一些用逗号分隔的字符串.有没有办法写一个sql来 对于通过逗号分隔而获得的每个令牌字符串,返回一个单独的行.
I have a table that stores some comma separated strings. Is there a way to write a sql to return me a separate rows for each token string obtained by splitting across commas.
推荐答案
您可以简单地编写和调用存储过程
You can simply write and call a stored procedure
DELIMITER $$
DROP PROCEDURE IF EXISTS explode_table $$
CREATE PROCEDURE explode_table(bound VARCHAR(255))
BEGIN
DECLARE id INT DEFAULT 0;
DECLARE value TEXT;
DECLARE occurance INT DEFAULT 0;
DECLARE i INT DEFAULT 0;
DECLARE splitted_value INT;
DECLARE done INT DEFAULT 0;
DECLARE cur1 CURSOR FOR SELECT table1.id, table1.value
FROM table1
WHERE table1.value != '';
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;
DROP TEMPORARY TABLE IF EXISTS table2;
CREATE TEMPORARY TABLE table2(
`id` INT NOT NULL,
`value` VARCHAR(255) NOT NULL
) ENGINE=Memory;
OPEN cur1;
read_loop: LOOP
FETCH cur1 INTO id, value;
IF done THEN
LEAVE read_loop;
END IF;
SET occurance = (SELECT LENGTH(value)
- LENGTH(REPLACE(value, bound, ''))
+1);
SET i=1;
WHILE i <= occurance DO
SET splitted_value =
(SELECT REPLACE(SUBSTRING(SUBSTRING_INDEX(value, bound, i),
LENGTH(SUBSTRING_INDEX(value, bound, i - 1)) + 1), ',', ''));
INSERT INTO table2 VALUES (id, splitted_value);
SET i = i + 1;
END WHILE;
END LOOP;
SELECT * FROM table2;
CLOSE cur1;
END; $$
-------------------
CALL explode_table(',');
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