从MySQL表的列中选择并仅显示一些行
让我们首先创建一个表-
mysql> create table DemoTable625 ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,StudentFirstName varchar(100),StudentScore int );
使用插入命令在表中插入一些记录-
mysql> insert into DemoTable625(StudentFirstName,StudentScore) values('John',98);
mysql> insert into DemoTable625(StudentFirstName,StudentScore) values('Chris',39);
mysql> insert into DemoTable625(StudentFirstName,StudentScore) values('Bob',41);
mysql> insert into DemoTable625(StudentFirstName,StudentScore) values('David',40);
mysql> insert into DemoTable625(StudentFirstName,StudentScore) values('Robert',52);使用select语句显示表中的所有记录-
mysql> select *from DemoTable625;
这将产生以下输出-
+-----------+------------------+--------------+ | StudentId | StudentFirstName | StudentScore | +-----------+------------------+--------------+ | 1 | John | 98 | | 2 | Chris | 39 | | 3 | Bob | 41 | | 4 | David | 40 | | 5 | Robert | 52 | +-----------+------------------+--------------+ 5 rows in set (0.00 sec)
这是用于选择和仅显示一些行的查询-
mysql> select *from DemoTable625 where StudentFirstName NOT IN( select StudentFirstName from DemoTable625 where StudentScore < 50 );
这将产生以下输出-
+-----------+------------------+--------------+ | StudentId | StudentFirstName | StudentScore | +-----------+------------------+--------------+ | 1 | John | 98 | | 5 | Robert | 52 | +-----------+------------------+--------------+ 2 rows in set (0.00 sec)