如何在MySQL中使用if子句，在新的列中显示学生的成绩（通过或不通过）？

首先让我们创建一个表 –

mysql> create table DemoTable
   -> (
   -> Id int NOT NULL AUTO_INCREMENT PRIMARY KEY,
   -> Name varchar(100),
   -> Subject varchar(100),
   -> Score int
   -> );
Query OK, 0 rows affected (0.94 sec)

使用插入命令向表中插入一些记录 –

mysql> insert into DemoTable(Name,Subject,Score) values('Chris','MySQL',80);
Query OK, 1 row affected (0.32 sec)

mysql> insert into DemoTable(Name,Subject,Score) values('Robert','MongoDB',45);
Query OK, 1 row affected (0.62 sec)

mysql> insert into DemoTable(Name,Subject,Score) values('Adam','Java',78);
Query OK, 1 row affected (0.52 sec)

使用SELECT语句从表中显示所有记录 –

mysql> select *from DemoTable;

阅读更多：MySQL 教程

输出

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)

这是使用MySQL中的if子句来显示结果（通过或失败）的查询。

mysql> select Name,Subject,Score,if(Score > 75,"PASS","FAIL") AS Status  from DemoTable;

输出

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)