“Reverse GROUP_CONCAT”在MySQL中? [英] "Reverse GROUP_CONCAT" in MySQL?

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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; $$

这篇关于“Reverse GROUP_CONCAT”在MySQL中?的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!

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