sql中的case when话语

 1 CREATE  TABLE `hello`.`sometbl` ( 2  3   `id` INT NOT NULL AUTO_INCREMENT , 4  5   `a` VARCHAR(45) NULL , 6  7   `b` VARCHAR(45) NULL , 8  9   `c` VARCHAR(45) NULL ,10 11   PRIMARY KEY (`id`) ,12 13   UNIQUE INDEX `id_UNIQUE` (`id` ASC) );

1 INSERT INTO `hello`.`sometbl` (`a`, `b`, `c`) VALUES ('1', '1', '0');2 3 INSERT INTO `hello`.`sometbl` (`b`, `c`) VALUES ('1', '1');4 5 INSERT INTO `hello`.`sometbl` (`a`, `c`) VALUES ('1', '1');6 7 INSERT INTO `hello`.`sometbl` (`b`) VALUES ('1');

SELECT * FROM hello.sometbl where ((case when a='1' then 1 else 0 end)+(case when b='1' then 1 else 0 end)+(case when c='1' then 1 else 0 end))=2;

SELECT id,case when id=1 then '一'when id=2 then '二'when id=3 then '三'when id=4 then '四'else '其它' end 中文数字FROM hello.sometbl;