mysql__CASE WHEN进行字符串替换处理

03  mysql> select * from sales;
04  +-----+------------+--------+--------+--------+------+------------+
05  | num | name       | winter | spring | summer | fall | category   |
06  +-----+------------+--------+--------+--------+------+------------+
07  |   1 | Java       |   1067 |    200 |    150 |  267 | Holiday    |
08  |   2 | C          |    970 |    770 |    531 |  486 | Profession |
09  |   3 | java script |     53 |     13 |     21 |  856 | Literary   |
10  |   4 | SQL        |    782 |    357 |    168 |  250 | Profession |
11  |   5 | Oracle     |    589 |    795 |    367 |  284 | Holiday    |
12  |   6 | MySQL      |    953 |    582 |    336 |  489 | Literary   |
13  |   7 | Cplus      |    752 |    657 |    259 |  478 | Literary   |
14  |   8 | Python     |     67 |     23 |     83 |  543 | Holiday    |
15  |   9 | PHP        |    673 |     48 |    625 |   52 | Profession |
16  +-----+------------+--------+--------+--------+------+------------+
17  9 rows in set (0.01 sec)
18 
19 mysql> SELECT name AS Name,
20     -> CASE category
21 
    -> WHEN "Holiday" THEN "Seasonal"//把sales表字段category中Holiday值替换为seasonal

22     -> WHEN "Profession" THEN "Bi_annual"
23     -> WHEN "Literary" THEN "Random" END AS "Pattern"//查询的结果命名为一个新的字段为pattern
24     -> FROM sales;
25  +------------+-----------+
26  | Name       | Pattern   |
27  +------------+-----------+
28  | Java       | Seasonal  |
29  | C          | Bi_annual |
30  | java script | Random    |
31  | SQL        | Bi_annual |
32  | Oracle     | Seasonal  |
33  | MySQL      | Random    |
34  | Cplus      | Random    |
35  | 





Python     | Seasonal  |
36  | PHP        | Bi_annual |
37  +------------+-----------+
38  9 rows in set (0.00 sec)
39 
40 
41  */
42  Drop table sales;
43     
44  CREATE TABLE sales(
45      num MEDIUMINT NOT NULL AUTO_INCREMENT,
46      name CHAR(20),
47      winter INT,
48      spring INT,
49      summer INT,
50      fall INT,
51      category CHAR(13),
52      primary key(num)
53  )type=MyISAM;
54 
55 
56  insert into sales value(1, 'Java', 1067 , 200, 150, 267,'Holiday');
57  insert into sales value(2, 'C',970,770,531,486,'Profession');
58  insert into sales value(3, 'java script',53,13,21,856,'Literary');
59  insert into sales value(4, 'SQL',782,357,168,250,'Profession');
60  insert into sales value(5, 'Oracle',589,795,367,284,'Holiday');
61  insert into sales value(6, 'MySQL',953,582,336,489,'Literary');
62  insert into sales value(7, 'Cplus',752,657,259,478,'Literary');
63  insert into sales value(8, 'Python',67,23,83,543,'Holiday');
64  insert into sales value(9, 'PHP',673,48,625,52,'Profession');
65 
66  select * from sales;
67 
68 
69  SELECT name AS Name,
70  CASE category
71  WHEN "Holiday" THEN "Seasonal"
72  WHEN "Profession" THEN "Bi_annual"
73  WHEN "Literary" THEN "Random" END AS "Pattern"
74  FROM sales;
SELECT num,name AS Name, case category
when "Holiday" then "1111"    #把categroy字段中的Holiday替换为1111
WHEN "Profession" THEN "2222" #把categroy字段中的Holiday替换为2222
WHEN "Literary" THEN "3333"   #把categroy字段中的Holiday替换为3333
END AS "从新命名标题"         #把categroy重新命名为'从新命名标题'
FROM sales;