“Reverse GROUP_CONCAT”在MySQL中? [英] "Reverse GROUP_CONCAT" in MySQL?
本文介绍了“Reverse GROUP_CONCAT”在MySQL中?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
+ ---这个问题似乎是针对这个问题的。 - + ---------------------- +
| id |颜色|
+ ---- + ---------------------- +
| 1 |红,绿,蓝|
| 2 | Orangered,长春|
+ ---- + ---------------------- +
但是我想把它格式化为这样:
+ ---- + ------------ +
| id |颜色|
+ ---- + ------------ +
| 1 |红色|
| 1 |绿色|
| 1 |蓝色|
| 2 | Orangered |
| 2 |长春|
+ ---- + ------------ +
<有没有一个很好的方法来做到这一点?什么是这种操作甚至叫?
解决方案
我想这是你需要的(存储过程): Mysql将列字符串拆分成行
DELIMITER $$
DROP PROCEDURE如果存在explode_table $$
CREATE PROCEDURE explode_table(bound VARCHAR(255))
BEGIN
DECLARE id INT DEFAULT 0;
DECLARE值TEXT;
DECLARE发生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!='';
声明未找到的继续处理程序SET = 1;
如果存在则删除临时表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;
如果完成了
则保留read_loop;
END IF;
$ b $ SET发生=(选择长度(值)
- 长度(REPLACE(value,bound,''))
+1);
SET i = 1; (SUBSTRING_INDEX(value,bound,i),
LENGTH(SUBSTRING_INDEX(value,bound,i));
WHILE i< =发生DO
SET splitted_value =
(SELECT REPLACE - 1))+ 1),',',''));
INSERT INTO table2 VALUES(id,splitted_value);
SET i = i + 1;
END WHILE;
END LOOP;
SELECT * FROM table2;
CLOSE cur1;
END; $$
I seem to come against this problem a lot, where I have data that's formatted like this:
+----+----------------------+
| id | colors |
+----+----------------------+
| 1 | Red,Green,Blue |
| 2 | Orangered,Periwinkle |
+----+----------------------+
but I want it formatted like this:
+----+------------+
| id | colors |
+----+------------+
| 1 | Red |
| 1 | Green |
| 1 | Blue |
| 2 | Orangered |
| 2 | Periwinkle |
+----+------------+
Is there a good way to do this? What is this kind of operation even called?
解决方案
I think it is what you need (stored procedure) : Mysql split column string into rows
DELIMITER $$
DROP PROCEDURE IF EXISTS explode_table $$
CREATE PROCEDURE explode_table(bound VARCHAR(255))
BEGIN
DECLARE id INT DEFAULT 0;
DECLARE value TEXT;
DECLARE occurance INT DEFAULT 0;
DECLARE i INT DEFAULT 0;
DECLARE splitted_value INT;
DECLARE done INT DEFAULT 0;
DECLARE cur1 CURSOR FOR SELECT table1.id, table1.value
FROM table1
WHERE table1.value != '';
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = 1;
DROP TEMPORARY TABLE IF EXISTS table2;
CREATE TEMPORARY TABLE table2(
`id` INT NOT NULL,
`value` VARCHAR(255) NOT NULL
) ENGINE=Memory;
OPEN cur1;
read_loop: LOOP
FETCH cur1 INTO id, value;
IF done THEN
LEAVE read_loop;
END IF;
SET occurance = (SELECT LENGTH(value)
- LENGTH(REPLACE(value, bound, ''))
+1);
SET i=1;
WHILE i <= occurance DO
SET splitted_value =
(SELECT REPLACE(SUBSTRING(SUBSTRING_INDEX(value, bound, i),
LENGTH(SUBSTRING_INDEX(value, bound, i - 1)) + 1), ',', ''));
INSERT INTO table2 VALUES (id, splitted_value);
SET i = i + 1;
END WHILE;
END LOOP;
SELECT * FROM table2;
CLOSE cur1;
END; $$
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