MySQL 的 CASE WHEN 语句 进行字符串替换处理

/* mysql> select * from sales; +-----+------------+--------+--------+--------+------+------------+ | num | name | winter | spring | summer | fall | category | +-----+------------+--------+--------+--------+------+------------+ | 1 | Java | 1067 | 200 | 150 | 267 | Holiday | | 2 | C | 970 | 770 | 531 | 486 | Profession | | 3 | JavaScript | 53 | 13 | 21 | 856 | Literary | | 4 | SQL | 782 | 357 | 168 | 250 | Profession | | 5 | Oracle | 589 | 795 | 367 | 284 | Holiday | | 6 | MySQL | 953 | 582 | 336 | 489 | Literary | | 7 | Cplus | 752 | 657 | 259 | 478 | Literary | | 8 | Python | 67 | 23 | 83 | 543 | Holiday | | 9 | PHP | 673 | 48 | 625 | 52 | Profession | +-----+------------+--------+--------+--------+------+------------+ 9 rows in set (0.01 sec) mysql> SELECT name AS Name, -> CASE category -> WHEN "Holiday" THEN "Seasonal" -> WHEN "Profession" THEN "Bi_annual" -> WHEN "Literary" THEN "Random" END AS "Pattern" -> FROM sales; +------------+-----------+ | Name | Pattern | +------------+-----------+ | Java | Seasonal | | C | Bi_annual | | JavaScript | Random | | SQL | Bi_annual | | Oracle | Seasonal | | MySQL | Random | | Cplus | Random | | Python | Seasonal | | PHP | Bi_annual | +------------+-----------+ 9 rows in set (0.00 sec) */ Drop table sales; CREATE TABLE sales( num MEDIUMINT NOT NULL AUTO_INCREMENT, name CHAR(20), winter INT, spring INT, summer INT, fall INT, category CHAR(13), primary key(num) )type=MyISAM; insert into sales value(1, 'Java', 1067 , 200, 150, 267,'Holiday'); insert into sales value(2, 'C',970,770,531,486,'Profession'); insert into sales value(3, 'JavaScript',53,13,21,856,'Literary'); insert into sales value(4, 'SQL',782,357,168,250,'Profession'); insert into sales value(5, 'Oracle',589,795,367,284,'Holiday'); insert into sales value(6, 'MySQL',953,582,336,489,'Literary'); insert into sales value(7, 'Cplus',752,657,259,478,'Literary'); insert into sales value(8, 'Python',67,23,83,543,'Holiday'); insert into sales value(9, 'PHP',673,48,625,52,'Profession'); select * from sales; SELECT name AS Name, CASE category WHEN "Holiday" THEN "Seasonal" WHEN "Profession" THEN "Bi_annual" WHEN "Literary" THEN "Random" END AS "Pattern" FROM sales;