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Legal Studies如何使用 MySQL 中的 if 子句將學生成績顯示為新一列中的“及格”或“不及格”
我們先建立一個表 −
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)
使用插入命令在表中插入一些記錄 −
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)使用選擇語句從表中顯示所有記錄 −
mysql> select *from DemoTable;
輸出
這將產生以下輸出 −
+----+--------+---------+-------+ | Id | Name | Subject | Score | +----+--------+---------+-------+ | 1 | Chris | MySQL | 80 | | 2 | Robert | MongoDB | 45 | | 3 | Adam | Java | 78 | +----+--------+---------+-------+ 3 rows in set (0.00 sec)
以下是使用 MySQL 中的 if 子句以“及格”或“不及格”形式顯示結果的查詢。
mysql> select Name,Subject,Score,if(Score > 75,"PASS","FAIL") AS Status from DemoTable;
輸出
這將產生以下輸出 −
+--------+---------+-------+--------+ | Name | Subject | Score | Status | +--------+---------+-------+--------+ | Chris | MySQL | 80 | PASS | | Robert | MongoDB | 45 | FAIL | | Adam | Java | 78 | PASS | +--------+---------+-------+--------+ 3 rows in set (0.00 sec)
更新於:30-Jun-2020
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