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MySQL交叉表實(shí)現(xiàn)分享

更新時(shí)間：2012年01月12日 21:07:19 作者：

在某些數(shù)據(jù)庫中有交叉表，但在MySQL中卻沒有這個(gè)功能，但網(wǎng)上看到有不少朋友想找出一個(gè)解決方法，特發(fā)貼集思廣義

現(xiàn)整理解法如下：

數(shù)據(jù)樣本：

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>

期望結(jié)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 生成匯總行,并利用 IFNULL將匯總行標(biāo)題顯示為 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 生成匯總行,并利用 IFNULL將匯總行標(biāo)題顯示為 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,直接生成結(jié)果不再利用子查詢
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. 動(dòng)態(tài)，適用于列不確定情況，
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>

以上均由網(wǎng)友 liangCK , wwwwb , WWWWA , dap570 提供, 再次感謝他們的支持。
其實(shí)數(shù)據(jù)庫中也可以用 CASE WHEN / DECODE 代替 IF

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