MySQL 5.7.16 字符串拆分 -> 單列變多行記錄(轉發）

http://blog.csdn.net/mchdba/article/details/53889803

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mysql> create table t1(c1 varchar(32),c2 varchar(32));
Query OK, 0 rows affected (0.02 sec)

mysql> INSERT INTO t1 SELECT 'man' c1,'123,234,567,789' c2 UNION ALL SELECT 'guo','-12,-87,-09,132' UNION ALL SELECT 'fang','1024,2387,1209,1032';
Query OK, 3 rows affected (0.02 sec)
Records: 3  Duplicates: 0  Warnings: 0

mysql> select * from t1;
+------+---------------------+
| c1   | c2                  |
+------+---------------------+
| man  | 123,234,567,789     |
| guo  | -12,-87,-09,132     |
| fang | 1024,2387,1209,1032 |
+------+---------------------+
3 rows in set (0.00 sec)

mysql>

 

需要達到的效果是，左邊變成右邊,按照逗號拆分出來,單列變成多行記錄，而且保留原來的其它列數據，如下圖所示：

 

 #,blog原地址：http://blog.csdn.net/mchdba/article/details/53889803，作者mchdba，謝絕轉載

 

這個復雜的實現，單條的sql或者幾條sql無法達到，需要臨時表存儲中間數據，所以編寫存儲過程，間接實現，存儲過程如下：

 

DELIMITER $$
USE `test`$$
DROP PROCEDURE IF EXISTS `proc_cur_split_str`$$
USE `test`$$
CREATE PROCEDURE test.proc_cur_split_str()
BEGIN
    DECLARE v_c1 VARCHAR(20);
    DECLARE v_c2 VARCHAR(60);
    DECLARE _done INT DEFAULT 0;

    DECLARE cur_strs CURSOR FOR SELECT c1,c2 from test.t1 ;
    DECLARE CONTINUE HANDLER FOR NOT FOUND BEGIN SET _done=1; END;
     DROP TABLE IF EXISTS test.ZZ_2;
     CREATE TABLE test.ZZ_2(C1 VARCHAR(20),CN VARCHAR(60));
    OPEN cur_strs;
        FETCH cur_strs INTO v_c1, v_c2;
        WHILE _done != 1  DO
            DROP TABLE IF EXISTS test.ZZ_1;
            CREATE TABLE ZZ_1(CN VARCHAR(60));
            SET @b=v_c2;
             SET @a = CONCAT(CONCAT("insert into test.ZZ_1 values('",REPLACE(@b,',',"'),('")),"')");
            -- SELECT @a;
             PREPARE stmt1 FROM @a;
            EXECUTE stmt1;
            -- SELECT v_c1,t.* FROM test.ZZ_1 t;
            INSERT INTO ZZ_2 SELECT v_c1,t.* FROM test.ZZ_1 t;

            COMMIT;
            -- SELECT * FROM test.ZZ_2;
            FETCH cur_strs INTO v_c1, v_c2;
    END WHILE;
    CLOSE cur_strs;
    SELECT * FROM test.ZZ_2;
END;

執行存儲過程，得到執行結果，符合心理預期，單列C1變成多行，並且保留了原來的其它字段c1的數據值，如下所示，