从 MySQL 表中的某一列中选择并仅显示部分行
mysqlmysqli database更新于 2023/10/18 8:06:00
首先我们创建一个表 −
mysql> create table DemoTable625 ( StudentId int NOT NULL AUTO_INCREMENT PRIMARY KEY,StudentFirstName varchar(100),StudentScore int ); Query OK, 0 rows affected (1.01 sec)
使用 insert 命令在表中插入一些记录 −
mysql> insert into DemoTable625(StudentFirstName,StudentScore) values('John',98);
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable625(StudentFirstName,StudentScore) values('Chris',39);
Query OK, 1 row affected (0.20 sec)
mysql> insert into DemoTable625(StudentFirstName,StudentScore) values('Bob',41);
Query OK, 1 row affected (0.11 sec)
mysql> insert into DemoTable625(StudentFirstName,StudentScore) values('David',40);
Query OK, 1 row affected (0.14 sec)
mysql> insert into DemoTable625(StudentFirstName,StudentScore) values('Robert',52);
Query OK, 1 row affected (0.18 sec)
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)
以下查询用于选择并仅显示某些行 −
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)
