Linux下Mysql的查詢用法

• 一、Mysql的delete刪除語法
• • 1.刪除數據庫
  • 2.刪除數據庫的表
• 二、查詢數據
• • 1.基本查詢
  • 2.條件查詢
• 三、數據庫插入數據
• • 1.創建新表
  • 2.插入數據
• 四、修改數據庫表內容

一、Mysql的delete刪除語法

1.刪除數據庫

①使用drop刪除

mysql> mysql> show databases; +--------------------+ | Database | +--------------------+ | huawei | | information_schema | | mysql | | performance_schema | | sys | | zabbix | +--------------------+ 6 rows in set (0.00 sec)mysql> drop database huawei; Query OK, 1 row affected (0.10 sec)mysql> show databases; +--------------------+ | Database | +--------------------+ | information_schema | | mysql | | performance_schema | | sys | | zabbix | +--------------------+ 5 rows in set (0.01 sec)mysql> flush privileges; Query OK, 0 rows affected (0.00 sec)

2.刪除數據庫的表

①使用drop語法

mysql> show tables; +------------------+ | Tables_in_zabbix | +------------------+ | student | +------------------+ 1 row in set (0.00 sec)mysql> drop table student; Query OK, 0 rows affected (0.05 sec)mysql> flush privileges; Query OK, 0 rows affected (0.00 sec)mysql> show tables; Empty set (0.00 sec)

二、查詢數據

語法：select _column,_column from _table [where Clause] [limit N][offset M]

1.基本查詢

select * from 表名 mysql> select * from fruits; +------+------+------------+---------+ | f_id | s_id | f_name | f_price | +------+------+------------+---------+ | a1 | 101 | apple | 5.20 | | b1 | 101 | blackberry | 10.20 | | bs1 | 102 | orange | 11.20 | | bs2 | 105 | melon | 7.20 | | t1 | 102 | banana | 10.30 | +------+------+------------+---------+ 5 rows in set (0.00 sec) mysql> select s_id from fruits; +------+ | s_id | +------+ | 101 | | 101 | | 102 | | 105 | | 102 | +------+ 5 rows in set (0.00 sec)

2.條件查詢

mysql> select s_id,f_name,f_price from fruits where f_price <=7; +------+--------+---------+ | s_id | f_name | f_price | +------+--------+---------+ | 101 | apple | 5.20 | +------+--------+---------+ 1 row in set (0.00 sec)

三、數據庫插入數據

1.創建新表

create table fruits ( f_id char(10) not null, s_id int not null, f_name char(255) not null, f_price decimal(8,2) not null, primary key(f_id) );

2.插入數據

mysql> insert into fruits(f_id,s_id,f_name,f_price) values ('bs2',105,'melon','7.2') ; Query OK, 1 row affected (0.00 sec)mysql> insert into fruits(f_id,s_id,f_name,f_price) values ('t1',102,'banana','10.3') ; Query OK, 1 row affected (0.05 sec) mysql> select * from fruits; +------+------+------------+---------+ | f_id | s_id | f_name | f_price | +------+------+------------+---------+ | a1 | 101 | apple | 5.20 | | b1 | 101 | blackberry | 10.20 | | bs1 | 102 | orange | 11.20 | | bs2 | 105 | melon | 7.20 | | t1 | 102 | banana | 10.30 | +------+------+------------+---------+ 5 rows in set (0.00 sec)

四、修改數據庫表內容

mysql> select * from fruits; +------+------+------------+---------+ | f_id | s_id | f_name | f_price | +------+------+------------+---------+ | a1 | 101 | apple | 5.20 | | b1 | 101 | blackberry | 10.20 | | bs1 | 102 | orange | 11.20 | | bs2 | 105 | melon | 7.20 | | t1 | 102 | banana | 10.30 | +------+------+------------+---------+ 5 rows in set (0.00 sec)mysql> UPDATE fruits SET f_price='8.5' WHERE f_id='a1'; Query OK, 1 row affected (0.05 sec) Rows matched: 1 Changed: 1 Warnings: 0mysql> select * from fruits; +------+------+------------+---------+ | f_id | s_id | f_name | f_price | +------+------+------------+---------+ | a1 | 101 | apple | 8.50 | | b1 | 101 | blackberry | 10.20 | | bs1 | 102 | orange | 11.20 | | bs2 | 105 | melon | 7.20 | | t1 | 102 | banana | 10.30 | +------+------+------------+---------+ 5 rows in set (0.00 sec)

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