MySQL中表的基本操作-2

 mysql> insert into teacher

     -> values (202, 'robot', 'ZhuHai', '2013-04-24');

 Query OK, 1 row affected (0.00 sec)

 

 mysql> insert into teacher

     -> values (203, 'Jack', 'ZhuHai', '2013-04-24');

 Query OK, 1 row affected (0.00 sec)

 

 mysql> insert into teacher

     -> values (204, 'Ann', 'ZhuHai', '2013-04-24');

 Query OK, 1 row affected (0.01 sec)

 

 mysql> insert into teacher

     -> values (205, 'Rose', 'ZhuHai', '2013-04-24');

 Query OK, 1 row affected (0.01 sec)

（1）统计有多少条记录

 mysql> select count(*) from teacher;

 +----------+

 | count(*) |

 +----------+

 |        4 |

 +----------+

 row in set (0.01 sec)

 

 mysql> select * from teacher;

 +-----+-------+---------+------------+

 | Id  | name  | address | year       |

 +-----+-------+---------+------------+

 | 202 | robot | ZhuHai  | 2013-04-24 |

 | 203 | Jack  | ZhuHai  | 2013-04-24 |

 | 204 | Ann   | ZhuHai  | 2013-04-24 |

 | 205 | Rose  | ZhuHai  | 2013-04-24 |

 +-----+-------+---------+------------+

 rows in set (0.00 sec)

（2）投影操作，选择需要查看的信息

 mysql> select Id, year from teacher;

 +-----+------------+

 | Id  | year       |

 +-----+------------+

 | 202 | 2013-04-24 |

 | 203 | 2013-04-24 |

 | 204 | 2013-04-24 |

 | 205 | 2013-04-24 |

 +-----+------------+

 rows in set (0.00 sec)



 mysql> select Id, name from teacher;

 +-----+-------+

 | Id  | name  |

 +-----+-------+

 | 202 | robot |

 | 203 | Jack  |

 | 204 | Ann   |

 | 205 | Rose  |

 +-----+-------+

 rows in set (0.00 sec)

（3）预览功能，显示字段中一部分的信息

 mysql> select Id, left(address, 3) from teacher;

 +-----+------------------+

 | Id  | left(address, 3) |

 +-----+------------------+

 | 202 | Zhu              |

 | 203 | Zhu              |

 | 204 | Zhu              |

 | 205 | Zhu              |

 +-----+------------------+

 rows in set (0.00 sec)

 

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