使用CASE WHEN进行字符串替换处理 复制代码 代码如下:mysql select * from sales; 9 rows in set (0.01 sec) SELECT name AS Name, CASE category WHEN "Holiday" THEN "Seasonal" WHEN "Profession" THEN "Bi_annual" WHEN "Literary" TH
使用CASE WHEN进行字符串替换处理复制代码 代码如下:mysql> select * from sales;
9 rows in set (0.01 sec)
SELECT name AS Name, CASE category WHEN "Holiday" THEN "Seasonal" WHEN "Profession" THEN "Bi_annual" WHEN "Literary" THEN "Random" END AS "Pattern"FROM sales;
9 rows in set (0.00 sec)
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)) ENGINE=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');简单语句复制代码 代码如下:SELECT CASE WHEN 10*2=30 THEN '30 correct' WHEN 10*2=40 THEN '40 correct' ELSE 'Should be 10*2=20'END AS `result`;多重表达式复制代码 代码如下:SELECT CASE 10*2 WHEN 20 THEN '20 correct' WHEN 30 THEN '30 correct' WHEN 40 THEN '40 correct' ELSE 'No results'END AS `result`;在SELECT查询中使用CASE WHEN复制代码 代码如下:CREATE TABLE DVDs ( ID SMALLINT NOT NULL AUTO_INCREMENT PRIMARY KEY, Name VARCHAR(60) NOT NULL, NumDisks TINYINT NOT NULL DEFAULT 1, RatingID VARCHAR(4) NOT NULL, StatID CHAR(3) NOT NULL) ENGINE=INNODB;INSERT INTO DVDs (Name, NumDisks, RatingID, StatID)VALUES ('Christmas', 1, 'NR', 's1'), ('Doc', 1, 'G', 's2'), ('Africa', 1, 'PG', 's1'), ('Falcon', 1, 'NR', 's2'), ('Amadeus', 1, 'PG', 's2'), ('Show', 2, 'NR', 's2'), ('View', 1, 'NR', 's1'), ('Mash', 2, 'R', 's2');SELECT Name, RatingID AS Rating, CASE RatingID WHEN 'R' THEN 'Under 17 requires an adult.' WHEN 'X' THEN 'No one 17 and under.' WHEN 'NR' THEN 'Use discretion when renting.' ELSE 'OK to rent to minors.' END AS PolicyFROM DVDsORDER BY Name;
8 rows in set (0.01 sec)
