在MySQL中如何使用if子句在新列中将学生成绩显示为“及格”或“不及格”
让我们首先创建一个表-
create table DemoTable -> ( -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY, -> Name varchar(100), -> Subject varchar(100), -> Score int -> );
使用插入命令在表中插入一些记录-
insert into DemoTable(Name,Subject,Score) values('Chris','MySQL',80);
insert into DemoTable(Name,Subject,Score) values('Robert','MongoDB',45);
insert into DemoTable(Name,Subject,Score) values('Adam','Java',78);使用select语句显示表中的所有记录-
select *from DemoTable;
输出结果
这将产生以下输出-
+----+--------+---------+-------+ | Id | Name | Subject | Score | +----+--------+---------+-------+ | 1 | Chris | MySQL | 80 | | 2 | Robert | MongoDB | 45 | | 3 | Adam | Java | 78 | +----+--------+---------+-------+ 3 rows in set (0.00 sec)
这是与MySQL中的if子句一起使用的查询，以及格或不及格的形式显示结果。
select Name,Subject,Score,if(Score > 75,"PASS","FAIL") AS Status from DemoTable;
输出结果
这将产生以下输出-
+--------+---------+-------+--------+ | Name | Subject | Score | Status | +--------+---------+-------+--------+ | Chris | MySQL | 80 | PASS | | Robert | MongoDB | 45 | FAIL | | Adam | Java | 78 | PASS | +--------+---------+-------+--------+ 3 rows in set (0.00 sec)