MySQL交叉表：纵向数据显示为横向

原文地址：https://my.oschina.net/MiniBu/blog/83233

 最近在处理一些数据，要实现纵向数据横向显示的效果，在百度花费多个小时东征西伐南讨北战之后，终于找到一个概括的较为详尽的文章，特地转载过来以便更多的人解决相关问题，希望原作者不要介怀。

    在某些数据库中有交叉表，但在MySQL中却没有这个功能，但网上看到有不少朋友想找出一个解决方法，特发贴集思广义。http://topic.csdn.net/u/20090530/23/0b782674-4b0b-4cf5-bc1a-e8914aaee5ab.html?96198

现整理解法如下： 

数据样本：

create table tx( 

 id int primary key, 

 c1 char(2), 

 c2 char(2), 

 c3 int 

);

insert into tx values 

(1 ,'A1','B1',9), 

(2 ,'A2','B1',7), 

(3 ,'A3','B1',4), 

(4 ,'A4','B1',2), 

(5 ,'A1','B2',2), 

(6 ,'A2','B2',9), 

(7 ,'A3','B2',8), 

(8 ,'A4','B2',5), 

(9 ,'A1','B3',1), 

(10 ,'A2','B3',8), 

(11 ,'A3','B3',8), 

(12 ,'A4','B3',6), 

(13 ,'A1','B4',8), 

(14 ,'A2','B4',2), 

(15 ,'A3','B4',6), 

(16 ,'A4','B4',9), 

(17 ,'A1','B4',3), 

(18 ,'A2','B4',5), 

(19 ,'A3','B4',2), 

(20 ,'A4','B4',5); 

mysql> select * from tx;

+----+------+------+------+

| id | c1   | c2   | c3   |

+----+------+------+------+

|  1 | A1   | B1   |    9 |

|  2 | A2   | B1   |    7 |

|  3 | A3   | B1   |    4 |

|  4 | A4   | B1   |    2 |

|  5 | A1   | B2   |    2 |

|  6 | A2   | B2   |    9 |

|  7 | A3   | B2   |    8 |

|  8 | A4   | B2   |    5 |

|  9 | A1   | B3   |    1 |

| 10 | A2   | B3   |    8 |

| 11 | A3   | B3   |    8 |

| 12 | A4   | B3   |    6 |

| 13 | A1   | B4   |    8 |

| 14 | A2   | B4   |    2 |

| 15 | A3   | B4   |    6 |

| 16 | A4   | B4   |    9 |

| 17 | A1   | B4   |    3 |

| 18 | A2   | B4   |    5 |

| 19 | A3   | B4   |    2 |

| 20 | A4   | B4   |    5 |

+----+------+------+------+

20 rows in set (0.00 sec)

mysql>

期望结果

+------+-----+-----+-----+-----+------+

|C1    |B1   |B2   |B3   |B4   |Total |

+------+-----+-----+-----+-----+------+

|A1    |9    |2    |1    |11   |23    |

|A2    |7    |9    |8    |7    |31    |

|A3    |4    |8    |8    |8    |28    |

|A4    |2    |5    |6    |14   |27    |

|Total |22   |24   |23   |40   |109   |

+------+-----+-----+-----+-----+------+

 

1. 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

mysql> SELECT

    ->     IFNULL(c1,'total') AS total,

    ->     SUM(IF(c2='B1',c3,0)) AS B1,

    ->     SUM(IF(c2='B2',c3,0)) AS B2,

    ->     SUM(IF(c2='B3',c3,0)) AS B3,

    ->     SUM(IF(c2='B4',c3,0)) AS B4,

    ->     SUM(IF(c2='total',c3,0)) AS total

    -> FROM (

    ->     SELECT c1,IFNULL(c2,'total') AS c2,SUM(c3) AS c3

    ->     FROM tx

    ->     GROUP BY c1,c2

    ->     WITH ROLLUP

    ->     HAVING c1 IS NOT NULL

    -> ) AS A

    -> GROUP BY c1

    -> WITH ROLLUP;

+-------+------+------+------+------+-------+

| total | B1   | B2   | B3   | B4   | total |

+-------+------+------+------+------+-------+

| A1    |    9 |    2 |    1 |   11 |    23 |

| A2    |    7 |    9 |    8 |    7 |    31 |

| A3    |    4 |    8 |    8 |    8 |    28 |

| A4    |    2 |    5 |    6 |   14 |    27 |

| total |   22 |   24 |   23 |   40 |   109 |

+-------+------+------+------+------+-------+

5 rows in set, 1 warning (0.00 sec)

 

 

2. 利用SUM(IF()) 生成列 + UNION 生成汇总行,并利用 IFNULL将汇总行标题显示为 Total
mysql> select c1,

    -> sum(if(c2='B1',C3,0)) AS B1,

    -> sum(if(c2='B2',C3,0)) AS B2,

    -> sum(if(c2='B3',C3,0)) AS B3,

    -> sum(if(c2='B4',C3,0)) AS B4,SUM(C3) AS TOTAL

    -> from tx

    -> group by C1

    -> UNION

    -> SELECT 'TOTAL',sum(if(c2='B1',C3,0)) AS B1,

    -> sum(if(c2='B2',C3,0)) AS B2,

    -> sum(if(c2='B3',C3,0)) AS B3,

    -> sum(if(c2='B4',C3,0)) AS B4,SUM(C3) FROM TX

    -> ;

+-------+------+------+------+------+-------+

| c1    | B1   | B2   | B3   | B4   | TOTAL |

+-------+------+------+------+------+-------+

| A1    |    9 |    2 |    1 |   11 |    23 |

| A2    |    7 |    9 |    8 |    7 |    31 |

| A3    |    4 |    8 |    8 |    8 |    28 |

| A4    |    2 |    5 |    6 |   14 |    27 |

| TOTAL |   22 |   24 |   23 |   40 |   109 |

+-------+------+------+------+------+-------+

5 rows in set (0.00 sec)

mysql>

 

3.  利用SUM(IF()) 生成列,直接生成结果不再利用子查询
mysql> select ifnull(c1,'total'),

    -> sum(if(c2='B1',C3,0)) AS B1,

    -> sum(if(c2='B2',C3,0)) AS B2,

    -> sum(if(c2='B3',C3,0)) AS B3,

    -> sum(if(c2='B4',C3,0)) AS B4,SUM(C3) AS TOTAL

    -> from tx

    -> group by C1 with rollup ;

+--------------------+------+------+------+------+-------+

| ifnull(c1,'total') | B1   | B2   | B3   | B4   | TOTAL |

+--------------------+------+------+------+------+-------+

| A1                 |    9 |    2 |    1 |   11 |    23 |

| A2                 |    7 |    9 |    8 |    7 |    31 |

| A3                 |    4 |    8 |    8 |    8 |    28 |

| A4                 |    2 |    5 |    6 |   14 |    27 |

| total              |   22 |   24 |   23 |   40 |   109 |

+--------------------+------+------+------+------+-------+

5 rows in set (0.00 sec)

mysql>

4. 动态，适用于列不确定情况，

mysql> SET @EE=''; 

mysql> SELECT @EE:=CONCAT(@EE,'SUM(IF(C2=/'',C2,'/'',',C3,0)) AS ',C2,',') FROM (SELECT DISTINCT C2 FROM TX) A; 

mysql> SET @QQ=CONCAT('SELECT ifnull(c1,/'total/'),',LEFT(@EE,LENGTH(@EE)-1),' ,SUM(C3) AS TOTAL FROM TX GROUP BY C1 WITH ROLLUP');

Query OK, 0 rows affected (0.00 sec)

mysql> PREPARE stmt2 FROM @QQ;

Query OK, 0 rows affected (0.00 sec)

Statement prepared

mysql> EXECUTE stmt2;

+--------------------+------+------+------+------+-------+

| ifnull(c1,'total') | B1   | B2   | B3   | B4   | TOTAL |

+--------------------+------+------+------+------+-------+

| A1                 |    9 |    2 |    1 |   11 |    23 |

| A2                 |    7 |    9 |    8 |    7 |    31 |

| A3                 |    4 |    8 |    8 |    8 |    28 |

| A4                 |    2 |    5 |    6 |   14 |    27 |

| total              |   22 |   24 |   23 |   40 |   109 |

+--------------------+------+------+------+------+-------+

5 rows in set (0.00 sec)

mysql>

 

以上均由网友  liangCK , wwwwb , WWWWA , dap570 提供, 再次感谢他们的支持。

 

其实数据库中也可以用 CASE WHEN / DECODE 代替 IF。