发布于 2016-02-29 04:18:13 | 94 次阅读 | 评论: 0 | 来源: 网友投递
Mysql关系型数据库管理系统
MySQL是一个开放源码的小型关联式数据库管理系统，开发者为瑞典MySQL AB公司。MySQL被广泛地应用在Internet上的中小型网站中。由于其体积小、速度快、总体拥有成本低，尤其是开放源码这一特点，许多中小型网站为了降低网站总体拥有成本而选择了MySQL作为网站数据库。
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