mysql__CASEWHEN进行字符串替换处理_MySQL

mysql__CASE WHEN进行字符串替换处理

使用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 | JavaScript |     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 category21     -> WHEN "Holiday" THEN "Seasonal"//把sales表字段category中Holiday值替换为seasonal22     -> 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pattern24     -> FROM sales;25  +------------+-----------+26  | Name       | Pattern   |27  +------------+-----------+28  | Java       | Seasonal  |29  | C          | Bi_annual |30  | JavaScript | 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, 'JavaScript',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 category71  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 categorywhen "Holiday" then "1111"    #把categroy字段中的Holiday替换为1111WHEN "Profession" THEN "2222" #把categroy字段中的Holiday替换为2222WHEN "Literary" THEN "3333"   #把categroy字段中的Holiday替换为3333END AS "从新命名标题"         #把categroy重新命名为'从新命名标题'FROM sales;