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法学从 MySQL 表中的列选择并显示某些行
首先，让我们创建一个表 -
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)
使用插入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)使用选择语句从表中显示所有记录 -
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)
以下是仅选择和显示某些行的查询 -
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)
更新于： 23-Aug-2019
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