动态mysql行列转换

一，列变成行例子演示

1，准备测试数据

USE csdn;
DROP TABLE IF EXISTS flow_table;
CREATE TABLE `flow_table` (
  `ID` INT(11) NOT NULL AUTO_INCREMENT,
  `Number` BIGINT(11) NOT NULL,
  `City` VARCHAR(10) NOT NULL,
  `wm201403` DECIMAL(7,2) DEFAULT NULL,
  `wm201404` DECIMAL(7,2) DEFAULT NULL,
  `wm201405` DECIMAL(7,2) DEFAULT NULL,
  `wm201406` DECIMAL(7,2) DEFAULT NULL,
  `wm201407` DECIMAL(7,2) DEFAULT NULL,
  `wm201408` DECIMAL(7,2) DEFAULT NULL,
  PRIMARY KEY (`ID`,`Number`)
) ENGINE=INNODB   DEFAULT CHARSET=utf8;
INSERT INTO flow_table(Number,City,wm201403,wm201404,wm201405,wm201406,wm201407,wm201408)SELECT 1,'shanghai',100.2,180.4,141,164,124,127;
INSERT INTO flow_table(Number,City,wm201403,wm201404,wm201405,wm201406,wm201407,wm201408)SELECT 2,'shanghai',110.23,180.34,141.23,104.78,124.67,127.45;
INSERT INTO flow_table(Number,City,wm201403,wm201404,wm201405,wm201406,wm201407,wm201408)SELECT 3,'beijing',123.23,110.34,131.33,154.58,154.67,167.45;
INSERT INTO flow_table(Number,City,wm201403,wm201404,wm201405,wm201406,wm201407,wm201408)SELECT 4,'hangzhou',0,110.34,131.33,154.58,154.67,0;
INSERT INTO flow_table(Number,City,wm201405,wm201406,wm201407,wm201408)SELECT 5,'hangzhou',131.33,154.58,154.67,0;

2，存储过程遍历：

这个存储过程建立了2张临时表，查询测试表数据形成游标，遍历游标根据主键Number来调用pro_flow_modify存储过程进行行列变化。代码如下：

DROP PROCEDURE IF EXISTS test.`proc_all_changes`;
CREATE PROCEDURE test.proc_all_changes()
BEGIN
    DECLARE v_number BIGINT;
    DECLARE v_city VARCHAR(10);
    DECLARE _done INT DEFAULT 0; 
    
    /*定义游标*/
    DECLARE cur_all CURSOR FOR SELECT Number,City FROM test.`flow_table`;
    /**这里如果需要定义下当NOT FOUND的时候，EXIT退出游标遍历，不然如果设置成CONTINUE会一直执行下去。*/
    DECLARE EXIT HANDLER FOR NOT FOUND BEGIN SET _done=1;END;      
    
       /*建立临时表，存放所有字段的临时表*/
	DROP TABLE IF EXISTS flow_n_columns;
	CREATE TABLE `flow_n_columns` (
	  `column_name` VARCHAR(10) NOT NULL
	) ENGINE=INNODB DEFAULT CHARSET=utf8;

	/*存放最终变成行的数据表*/
	DROP TABLE IF EXISTS flow_tmp;
	CREATE TABLE `flow_tmp` (
	  `Number` INT(11) DEFAULT NULL,
	  `City` VARCHAR(10) DEFAULT NULL,
	  `wm_str` VARCHAR(10) DEFAULT NULL,
	  `Wm` DECIMAL(7,2) DEFAULT NULL
	) ENGINE=INNODB DEFAULT CHARSET=utf8;

    OPEN cur_all;
    REPEAT
        FETCH cur_all INTO v_number, v_city;
        IF NOT _done THEN 
		CALL test.pro_flow_modify(v_number,v_city);
        END IF; 
        UNTIL _done=1 END REPEAT;
    CLOSE cur_all; 
    	/*展示下所有的行转列的数据**/
	SELECT * FROM test.flow_tmp;      
END

3，行里变化存储过程

通过查询系统表information_schema.`COLUMNS`来获取测试表flow_table的所有列，然后写动态SQL，来把列的值录入到临时表flow_tmp中。

DROP PROCEDURE IF EXISTS test.`pro_flow_modify`;
CREATE PROCEDURE test.`pro_flow_modify`(p_Number INT,p_city VARCHAR(10))
BEGIN
	DECLARE v_column_name VARCHAR(10) DEFAULT '';
	DECLARE v_exe_sql VARCHAR(1000) DEFAULT '';
	DECLARE v_start_wm VARCHAR(10) DEFAULT '';
	DECLARE v_end_wm VARCHAR(10) DEFAULT '';
	DECLARE v_num  DECIMAL(10,2) DEFAULT 0;
	
	DECLARE i INT DEFAULT 1;
	DECLARE v_Number INT DEFAULT 0;
	SET v_Number=p_Number;
	
	DELETE FROM test.flow_n_columns;
	DELETE FROM test.flow_tmp WHERE Number=v_Number;
	
	
	/*把测试表flow_table的所有字段都录入字段临时表中，这样就达到了从列变成行的目的*/
	INSERT INTO flow_n_columns
	SELECT t.`COLUMN_NAME` FROM information_schema.`COLUMNS` t WHERE t.`TABLE_NAME`='flow_table' AND t.`TABLE_SCHEMA`='test' AND t.`COLUMN_NAME` NOT IN('ID','Number','City');
	SELECT column_name INTO v_column_name FROM test.flow_n_columns LIMIT 1;
	
	/*开始循环遍历字段临时表的字段数据，并且把字段值放入临时表flow_tmp里面*/
	WHILE i>0 DO
		SET v_exe_sql=CONCAT('INSERT INTO test.flow_tmp(Number,City,wm_str,Wm) select ',v_Number,',\'',p_city, '\',\'',v_column_name,'\',',v_column_name,' from test.flow_table WHERE flow_table.Number=',v_Number,';');
		SET @sql=v_exe_sql;
		PREPARE s1 FROM @sql;
		EXECUTE s1;
		DEALLOCATE PREPARE s1; 
		DELETE FROM test.flow_n_columns WHERE column_name=v_column_name;
		SELECT column_name INTO v_column_name FROM test.flow_n_columns LIMIT 1;
		SELECT COUNT(1) INTO i FROM test.flow_n_columns ;
		DELETE FROM test.flow_tmp WHERE Wm=0;
	END WHILE;

	/*由于触发器是不支持动态sql，所以不能使用while循环，动态遍历所有统计列的，只能写死列了，如下所示：
	现在一个个insert只能写死了, flow_table表有多少个统计列就写多少个insert sql，以后新添加一个列，就在这里新添加一条insertsql语句
	INSERT INTO flow_tmp(Number,City,wm_str,Wm) SELECT v_Number,p_city,'wm201403',wm201403 FROM flow_table WHERE Number=v_Number ;
	INSERT INTO flow_tmp(Number,City,wm_str,Wm) SELECT v_Number,p_city,'wm201404',wm201404 FROM flow_table WHERE Number=v_Number ;
	INSERT INTO flow_tmp(Number,City,wm_str,Wm) SELECT v_Number,p_city,'wm201405',wm201405 FROM flow_table WHERE Number=v_Number ;
	INSERT INTO flow_tmp(Number,City,wm_str,Wm) SELECT v_Number,p_city,'wm201406',wm201406 FROM flow_table WHERE Number=v_Number ;
	INSERT INTO flow_tmp(Number,City,wm_str,Wm) SELECT v_Number,p_city,'wm201407',wm201407 FROM flow_table WHERE Number=v_Number ;
	INSERT INTO flow_tmp(Number,City,wm_str,Wm) SELECT v_Number,p_city,'wm201408',wm201408 FROM flow_table WHERE Number=v_Number ;
	*/
	
	/*清除掉不数据=0的列*/
	DELETE FROM test.flow_tmp WHERE Wm=0 OR Wm IS NULL;
	
	SELECT wm_str INTO v_start_wm FROM test.flow_tmp WHERE Number=v_Number ORDER BY wm_str ASC LIMIT 1;
	SELECT wm_str INTO v_end_wm FROM test.flow_tmp WHERE Number=v_Number ORDER BY wm_str DESC LIMIT 1;
	SELECT SUM(Wm) INTO v_num FROM test.flow_tmp WHERE Number=v_Number;	
	

    END

4，列变行结果展示

临时表的所有数据：

mysql> SELECT * FROM flow_tmp;  
+--------+----------+----------+--------+  
| Number | City     | wm_str   | Wm     |  
+--------+----------+----------+--------+  
|      1 | shanghai | wm201403 | 100.20 |  
|      1 | shanghai | wm201404 | 180.40 |  
|      1 | shanghai | wm201405 | 141.00 |  
|      1 | shanghai | wm201406 | 164.00 |  
|      1 | shanghai | wm201407 | 124.00 |  
|      1 | shanghai | wm201408 | 127.00 |  
|      2 | shanghai | wm201403 | 110.23 |  
|      2 | shanghai | wm201404 | 180.34 |  
|      2 | shanghai | wm201405 | 141.23 |  
|      2 | shanghai | wm201406 | 104.78 |  
|      2 | shanghai | wm201407 | 124.67 |  
|      2 | shanghai | wm201408 | 127.45 |  
|      3 | beijing  | wm201403 | 123.23 |  
|      3 | beijing  | wm201404 | 110.34 |  
|      3 | beijing  | wm201405 | 131.33 |  
|      3 | beijing  | wm201406 | 154.58 |  
|      3 | beijing  | wm201407 | 154.67 |  
|      3 | beijing  | wm201408 | 167.45 |  
|      4 | hangzhou | wm201404 | 110.34 |  
|      4 | hangzhou | wm201405 | 131.33 |  
|      4 | hangzhou | wm201406 | 154.58 |  
|      4 | hangzhou | wm201407 | 154.67 |  
|      5 | hangzhou | wm201405 | 131.33 |  
|      5 | hangzhou | wm201406 | 154.58 |  
|      5 | hangzhou | wm201407 | 154.67 |  
+--------+----------+----------+--------+  
25 rows in set (0.00 sec)

统计每个用户的使用总量为：

mysql> SELECT Number,SUM(Wm) 'total_num' FROM flow_tmp GROUP BY Number ORDER BY Number;  
+--------+-----------+  
| Number | total_num |  
+--------+-----------+  
|      1 |    836.60 |  
|      2 |    788.70 |  
|      3 |    841.60 |  
|      4 |    550.92 |  
|      5 |    440.58 |  
+--------+-----------+  
5 rows in set (0.00 sec)

二，行变列例子演示

1，准备测试数据

DROP TABLE IF EXISTS tb;  
CREATE TABLE tb(`cname` VARCHAR(10),cource VARCHAR(10),score INT) ENGINE=INNODB;  
  
INSERT INTO tb VALUES('张三','语文',74);  
INSERT INTO tb VALUES('张三','数学',83);  
INSERT INTO tb VALUES('张三','物理',93);  
INSERT INTO tb VALUES('李四','语文',74);  
INSERT INTO tb VALUES('李四','数学',84);  
INSERT INTO tb VALUES('李四','物理',94);  
  
SELECT * FROM tb;

需要得到的结果是：

2，利用SUM(IF()) 生成列 + WITH ROLLUP 生成汇总行,并利用 IFNULL将汇总行标题显示为 Total_num

SQL代码块如下：

SELECT cname AS "姓名",  
    SUM(IF(cource="语文",score,0)) AS "语文",  
    SUM(IF(cource="数学",score,0)) AS "数学",  
    SUM(IF(cource="物理",score,0)) AS "物理",  
    SUM(score) AS "总成绩",  
    ROUND(AVG(score),2) AS "平均成绩"  
FROM tb   
GROUP BY cname  
UNION ALL  
SELECT  
    "总成绩平均数",  
    ROUND(AVG(`语文`),2) , ROUND(AVG(`数学`),2), ROUND(AVG(`物理`),2), ROUND(AVG(`总成绩`),2), ROUND(AVG(`平均成绩`),2)  
FROM(  
    SELECT "all",cname AS "姓名",  
        SUM(IF(cource="语文",score,0)) AS "语文",  
        SUM(IF(cource="数学",score,0)) AS "数学",  
        SUM(IF(cource="物理",score,0)) AS "物理",  
        SUM(score) AS "总成绩",  
        AVG(score) AS "平均成绩"  
    FROM tb   
    GROUP BY cname  
)tb2   
GROUP BY tb2.all;

执行结果正确，如下所示：

3，利用max(CASE ... WHEN ... THEN .. ELSE END) AS "语文"的方式来实现

SQL代码如下：

SELECT   
    cname AS "姓名",  
    MAX(CASE cource WHEN "语文" THEN score ELSE 0 END) AS "语文",   
    MAX(CASE cource WHEN "数学" THEN score ELSE 0 END) AS "数学",   
    MAX(CASE cource WHEN "物理" THEN score ELSE 0 END) AS "物理",   
    SUM(score) AS "总成绩",  
    ROUND(AVG(score) ,2) AS "平均成绩"  
FROM tb   
GROUP BY `cname`  
UNION ALL  
SELECT  
    "总成绩平均数",  
    ROUND(AVG(`语文`),2) , ROUND(AVG(`数学`),2), ROUND(AVG(`物理`),2), ROUND(AVG(`总成绩`),2), ROUND(AVG(`平均成绩`),2)  
FROM(   SELECT 'all' ,    
        cname AS "姓名",  
        MAX(CASE cource WHEN "语文" THEN score ELSE 0 END) AS "语文",   
        MAX(CASE cource WHEN "数学" THEN score ELSE 0 END) AS "数学",   
        MAX(CASE cource WHEN "物理" THEN score ELSE 0 END) AS "物理",   
        SUM(score) AS "总成绩",  
        ROUND(AVG(score) ,2) AS "平均成绩"  
    FROM tb   
    GROUP BY `cname`   
)tb2 GROUP BY tb2.all

执行结果正确，如下所示：

4，利用 WITH rollup结果不符合

SQL代码如下：

SELECT IFNULL(cname,'总平均数') AS "姓名",  
MAX(CASE cource WHEN "语文" THEN score ELSE 0 END) AS "语文",   
MAX(CASE cource WHEN "数学" THEN score ELSE 0 END) AS "数学",   
MAX(CASE cource WHEN "物理" THEN score ELSE 0 END) AS "物理",   
ROUND(AVG(score),2) AS "总成绩",  
ROUND(AVG(avg_score),2) AS "平均成绩"   
   FROM(  
SELECT     
    cname ,  
    IFNULL(cource,'total') cource,  
    SUM(score) AS score,  
    ROUND(AVG(score) ,2) AS avg_score  
FROM tb   
GROUP BY `cname`,cource WITH ROLLUP HAVING cname IS NOT NULL  
)tb2   
GROUP BY  tb2.cname WITH ROLLUP;

执行结果不对，总平均数栏目，里面各科比较语文数学的班级平均数不对，如下所示：

mysql>     SELECT IFNULL(cname,'总平均数') AS "姓名",  
    -> MAX(CASE cource WHEN "语文" THEN score ELSE 0 END) AS "语文",   
    -> MAX(CASE cource WHEN "数学" THEN score ELSE 0 END) AS "数学",   
    -> MAX(CASE cource WHEN "物理" THEN score ELSE 0 END) AS "物理",   
    -> ROUND(AVG(score),2) AS "总成绩",  
    -> ROUND(AVG(avg_score),2) AS "平均成绩"   
    ->     FROM(  
    -> SELECT     
    ->   
Display ALL 793 possibilities? (Y OR n)   
    -> cname ,  
    ->   
Display ALL 793 possibilities? (Y OR n)   
    -> IFNULL(cource,'total') cource,  
    ->   
Display ALL 793 possibilities? (Y OR n)   
    -> SUM(score) AS score,  
    ->   
Display ALL 793 possibilities? (Y OR n)   
    -> ROUND(AVG(score) ,2) AS avg_score  
    -> FROM tb   
    -> GROUP BY `cname`,cource WITH ROLLUP HAVING cname IS NOT NULL  
    -> )tb2   
    -> GROUP BY  tb2.cname WITH ROLLUP;  
+--------------+--------+--------+--------+-----------+--------------+  
| 姓名         | 语文   | 数学   | 物理   | 总成绩    | 平均成绩     |  
+--------------+--------+--------+--------+-----------+--------------+  
| 张三         |     74 |     83 |     93 |    125.00 |        83.33 |  
| 李四         |     74 |     84 |     94 |    126.00 |        84.00 |  
| 总平均数     |     74 |     84 |     94 |    125.50 |        83.67 |  
+--------------+--------+--------+--------+-----------+--------------+  
3 ROWS IN SET, 1 warning (0.00 sec)

总结： WITH rollup中对求列的总数是OK的，但是求列的平均数有偏差，这里场景使用不是恰当。

5，使用动态SQL来实现

SQL代码块如下：

/*仅仅班级成员部分*/  
SET @a='';   
SELECT @a:=CONCAT(@a,'SUM(IF(cource=\'',cource,'\'',',score,0)) AS ',cource,',') FROM (SELECT DISTINCT cource FROM tb) A;  
SET @a=CONCAT(@a,"ROUND(AVG(score) ,2) AS \"平均成绩\"");  
SET @b=CONCAT('SELECT IFNULL(cname,\'总成绩\'),',LEFT(@a,LENGTH(@a)-1),' ,SUM(score) AS \"总成绩\" FROM tb GROUP BY cname ');  
  
/*班级成员总计部分**/  
SET @a2="";  
SET @b2=CONCAT('SELECT "all",IFNULL(cname,\'总成绩\'),',LEFT(@a,LENGTH(@a)-1),' ,SUM(score) AS \"总成绩\" FROM tb GROUP BY cname ');  
SELECT @a2:=CONCAT(@a2,'ROUND(AVG(`',cource,'`),2),') FROM (SELECT DISTINCT cource FROM tb) A;  
SET @a2=CONCAT(@a2," ROUND(AVG(`平均成绩`),2),ROUND(AVG(`总成绩`),2) ");  
SET @c=CONCAT("SELECT \"班级平均数\",",LEFT(@a2,LENGTH(@a)-1)," FROM(",@b2,")tb2 GROUP BY tb2.all;");  
SET @d=CONCAT(@b," UNION ALL ",@c);  
  
PREPARE stmt1 FROM @d;  
EXECUTE stmt1;

查看执行结果如下，已经达到效果：

mysql> /*仅仅班级成员部分*/  
mysql> SET @a='';   
QUERY OK, 0 ROWS affected (0.00 sec)  
  
mysql> SELECT @a:=CONCAT(@a,'SUM(IF(cource=\'',cource,'\'',',score,0)) AS ',cource,',') FROM (SELECT DISTINCT cource FROM tb) A;  
+-----------------------------------------------------------------------------------------------------------------------------------+  
| @a:=CONCAT(@a,'SUM(IF(cource=\'',cource,'\'',',score,0)) AS ',cource,',')                                                         |  
+-----------------------------------------------------------------------------------------------------------------------------------+  
| SUM(IF(cource='语文',score,0)) AS 语文,                                                                                           |  
| SUM(IF(cource='语文',score,0)) AS 语文,SUM(IF(cource='数学',score,0)) AS 数学,                                                    |  
| SUM(IF(cource='语文',score,0)) AS 语文,SUM(IF(cource='数学',score,0)) AS 数学,SUM(IF(cource='物理',score,0)) AS 物理,             |  
+-----------------------------------------------------------------------------------------------------------------------------------+  
3 ROWS IN SET (0.00 sec)  
  
mysql> SET @a=CONCAT(@a,"ROUND(AVG(score) ,2) AS \"平均成绩\"");  
QUERY OK, 0 ROWS affected (0.00 sec)  
  
mysql> SET @b=CONCAT('SELECT IFNULL(cname,\'总成绩\'),',LEFT(@a,LENGTH(@a)-1),' ,SUM(score) AS \"总成绩\" FROM tb GROUP BY cname ');  
QUERY OK, 0 ROWS affected (0.00 sec)  
  
mysql>   
mysql> /*班级成员总计部分**/  
mysql> SET @a2="";  
QUERY OK, 0 ROWS affected (0.00 sec)  
  
mysql> SET @b2=CONCAT('SELECT "all",IFNULL(cname,\'总成绩\'),',LEFT(@a,LENGTH(@a)-1),' ,SUM(score) AS \"总成绩\" FROM tb GROUP BY cname ');  
QUERY OK, 0 ROWS affected (0.00 sec)  
  
mysql> SELECT @a2:=CONCAT(@a2,'ROUND(AVG(`',cource,'`),2),') FROM (SELECT DISTINCT cource FROM tb) A;  
+-----------------------------------------------------------------------+  
| @a2:=CONCAT(@a2,'ROUND(AVG(`',cource,'`),2),')                        |  
+-----------------------------------------------------------------------+  
| ROUND(AVG(`语文`),2),                                                 |  
| ROUND(AVG(`语文`),2),ROUND(AVG(`数学`),2),                            |  
| ROUND(AVG(`语文`),2),ROUND(AVG(`数学`),2),ROUND(AVG(`物理`),2),       |  
+-----------------------------------------------------------------------+  
3 ROWS IN SET (0.00 sec)  
  
mysql> SET @a2=CONCAT(@a2," ROUND(AVG(`平均成绩`),2),ROUND(AVG(`总成绩`),2) ");  
QUERY OK, 0 ROWS affected (0.00 sec)  
  
mysql> SET @c=CONCAT("SELECT \"班级平均数\",",LEFT(@a2,LENGTH(@a)-1)," FROM(",@b2,")tb2 GROUP BY tb2.all;");  
QUERY OK, 0 ROWS affected (0.00 sec)  
  
mysql> SET @d=CONCAT(@b," UNION ALL ",@c);  
QUERY OK, 0 ROWS affected (0.00 sec)  
  
mysql>   
mysql> PREPARE stmt1 FROM @d;  
QUERY OK, 0 ROWS affected (0.00 sec)  
Statement prepared  
  
mysql> EXECUTE stmt1;  
+---------------------------+--------+--------+--------+--------------+-----------+  
| IFNULL(cname,'总成绩')    | 语文   | 数学   | 物理   | 平均成绩     | 总成绩    |  
+---------------------------+--------+--------+--------+--------------+-----------+  
| 张三                      |  74.00 |  83.00 |  93.00 |        83.33 |    250.00 |  
| 李四                      |  74.00 |  84.00 |  94.00 |        84.00 |    252.00 |  
| 班级平均数                |  74.00 |  83.50 |  93.50 |        83.67 |    251.00 |  
+---------------------------+--------+--------+--------+--------------+-----------+  
3 ROWS IN SET (0.00 sec)

动态mysql行列转换

1，准备测试数据

2，存储过程遍历：

3，行里变化存储过程

4，列变行结果展示

1，准备测试数据

2，利用SUM(IF()) 生成列 + WITH ROLLUP 生成汇总行,并利用 IFNULL将汇总行标题显示为 Total_num

3，利用max(CASE ... WHEN ... THEN .. ELSE END) AS "语文"的方式来实现

4，利用 WITH rollup结果不符合

5，使用动态SQL来实现

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