MySQL5.7常用命令

1、连接mysql

  1. 连接本机

    mysql -u root -p
  2. 连接远程主机

    mysql -h 192.168.1.% -u root -p
  3. 退出

    exit;

2、修改密码

格式:alter user 用户名@主机地址 identified by '新密码';

  1. 将root密码改为newroot

    alter user root@local identified by 'newroot';
  2. 查看用户主机地址方法

    use mysql;
    select user,host from user;

3、管理用户

可以管理mysql数据库中的user表来管理用户。

对于用户方面的管理,最好对用户授予不同的权限来管理用户。

增加tom用户,密码为tom,可在任何主机登录:

create user 'tom'@localhost identified by 'tom';
create user 'tom1'@'192.168.1.%' identified by 'tom1';

4、管理数据库

  1. 显示数据库

    show databases;

    注:数据库乱码问题

    1. 修改/etc/my.cnf配置文件:character-set-server=utf8

    2. Java连接mysql的配置文件中:

      jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8;

     

  2. 创建数据库

    create database db_name;

     

  3. 删除数据库

    drop database if exists db_name;
  4. 使用数据库

    mysql> use db_name;
    Database changed
  5. 当前选择的数据库

    select database();

    MySQL中select命令类似于其他编程语言里的print或者write,你可以用它来显示一个字符串、数字、数学表达式的结果等等。部分select命令如下:

    select version();               // 显示mysql版本
    select now();                   // 显示当前时间
    select current_date;            // 显示年月日
    select ((4 * 7) / 10 ) + 23;    // 计算

5、管理表

  1. 显示所有表

    show tables;
  2. 查看表结构

    (1)方式一:

    mysql> desc orders;
    +------------+----------+------+-----+---------+----------------+
    | Field     | Type     | Null | Key | Default | Extra         |
    +------------+----------+------+-----+---------+----------------+
    | order_num  | int(11)  | NO   | PRI | NULL   | auto_increment |
    | order_date | datetime | NO   |     | NULL   |               |
    | cust_id   | int(11)  | NO   | MUL | NULL   |               |
    +------------+----------+------+-----+---------+----------------+
    3 rows in set (0.24 sec)

    (2)方式二:

    mysql> show columns from orders;
    +------------+----------+------+-----+---------+----------------+
    | Field     | Type     | Null | Key | Default | Extra         |
    +------------+----------+------+-----+---------+----------------+
    | order_num  | int(11)  | NO   | PRI | NULL   | auto_increment |
    | order_date | datetime | NO   |     | NULL   |               |
    | cust_id   | int(11)  | NO   | MUL | NULL   |               |
    +------------+----------+------+-----+---------+----------------+
    3 rows in set (0.00 sec)

    (3)方式三:

    mysql> show create table orders\G;
    *************************** 1. row ***************************
           Table: orders
    Create Table: CREATE TABLE `orders` (
      `order_num` int(11) NOT NULL AUTO_INCREMENT,
      `order_date` datetime NOT NULL,
      `cust_id` int(11) NOT NULL,
      PRIMARY KEY (`order_num`),
      KEY `fk_orders_customers` (`cust_id`),
      CONSTRAINT `fk_orders_customers` FOREIGN KEY (`cust_id`) REFERENCES `customers` (`cust_id`)
    ) ENGINE=InnoDB AUTO_INCREMENT=20011 DEFAULT CHARSET=utf8
    1 row in set (0.00 sec)
    ​
    ERROR: 
    No query specified

    (4)方式四:

    mysql> show full fields from orders;
    +------------+----------+-----------+------+-----+---------+----------------+---------------------------------+---------+
    | Field     | Type     | Collation | Null | Key | Default | Extra         | Privileges                     | Comment |
    +------------+----------+-----------+------+-----+---------+----------------+---------------------------------+---------+
    | order_num  | int(11)  | NULL     | NO   | PRI | NULL   | auto_increment | select,insert,update,references |         |
    | order_date | datetime | NULL     | NO   |     | NULL   |               | select,insert,update,references |         |
    | cust_id   | int(11)  | NULL     | NO   | MUL | NULL   |               | select,insert,update,references |         |
    +------------+----------+-----------+------+-----+---------+----------------+---------------------------------+---------+
    3 rows in set (0.00 sec)

    (5)方式五:

    mysql> show fields from orders;
    +------------+----------+------+-----+---------+----------------+
    | Field     | Type     | Null | Key | Default | Extra         |
    +------------+----------+------+-----+---------+----------------+
    | order_num  | int(11)  | NO   | PRI | NULL   | auto_increment |
    | order_date | datetime | NO   |     | NULL   |               |
    | cust_id   | int(11)  | NO   | MUL | NULL   |               |
    +------------+----------+------+-----+---------+----------------+
    3 rows in set (0.00 sec)

    (6)方式六:查看表中某个字段

    mysql> desc orders order_num;
    +-----------+---------+------+-----+---------+----------------+
    | Field     | Type   | Null | Key | Default | Extra         |
    +-----------+---------+------+-----+---------+----------------+
    | order_num | int(11) | NO   | PRI | NULL   | auto_increment |
    +-----------+---------+------+-----+---------+----------------+
    1 row in set (0.00 sec)

    (7)方式七:查看表中索引

    mysql> show index from orders\G;
    *************************** 1. row ***************************
            Table: orders
       Non_unique: 0
         Key_name: PRIMARY
     Seq_in_index: 1
      Column_name: order_num
        Collation: A
      Cardinality: 5
         Sub_part: NULL
           Packed: NULL
             Null: 
       Index_type: BTREE
          Comment: 
    Index_comment: 
    *************************** 2. row ***************************
            Table: orders
       Non_unique: 1
         Key_name: fk_orders_customers
     Seq_in_index: 1
      Column_name: cust_id
        Collation: A
      Cardinality: 4
         Sub_part: NULL
           Packed: NULL
             Null: 
       Index_type: BTREE
          Comment: 
    Index_comment: 
    2 rows in set (0.00 sec)
    ​
    ERROR: 
    No query specified
  3. 创建表:建立一个名为test的表

    mysql> create table test(
       -> id INT(11) NOT NULL AUTO_INCREMENT,
       -> name VARCHAR(255) NOT NULL,
       -> PRIMARY KEY (id)
       -> );
    Query OK, 0 rows affected (0.44 sec)
  4. 删除表

    mysql> drop table if exists test;
    Query OK, 0 rows affected (0.20 sec)
  5. 向表中插入数据:

    格式:insert into 表名 ( 字段名1,···, 字段名n ) values ( 值1, ···, 值n );

    mysql> insert into test (name) values ("zhangsan");
    Query OK, 1 row affected (0.14 sec)
    ​
    mysql> select * from test;
    +----+----------+
    | id | name     |
    +----+----------+
    |  1 | zhangsan |
    +----+----------+
    1 row in set (0.02 sec)

    插入多条记录:

    mysql> insert into test (name) values ("lisi"),("xiaoming");
    Query OK, 2 rows affected (0.04 sec)
    Records: 2  Duplicates: 0  Warnings: 0
    ​
    mysql> select * from test;
    +----+----------+
    | id | name     |
    +----+----------+
    |  1 | zhangsan |
    |  2 | lisi     |
    |  3 | xiaoming |
    +----+----------+
    3 rows in set (0.00 sec)
  6. 查询表数据

    格式: select 字段1, ···, 字段n from 表名 where 表达式

    (1)查询表所有:

    mysql> select * from test;
    +----+----------+
    | id | name     |
    +----+----------+
    |  1 | zhangsan |
    |  2 | lisi     |
    |  3 | xiaoming |
    +----+----------+
    3 rows in set (0.00 sec)

    (2)查询前两行:

    mysql> select * from test limit 2;
    +----+----------+
    | id | name     |
    +----+----------+
    |  1 | zhangsan |
    |  2 | lisi     |
    +----+----------+
    2 rows in set (0.03 sec)
  7. 删除表数据

    格式:delete from 表名 where 表达式

    mysql> delete from test where id = 2;
    Query OK, 1 row affected (0.13 sec)
    ​
    mysql> select * from test;
    +----+----------+
    | id | name     |
    +----+----------+
    |  1 | zhangsan |
    |  3 | xiaoming |
    +----+----------+
    2 rows in set (0.00 sec)
  8. 修改表数据

    格式:UPDATE [LOW_PRIORITY] tbl_name SET col_name1=expr1 [, col_name2=expr2 ...] [WHERE where_definition] [ORDER BY ...] [LIMIT row_count]

    • UPDATE语法可以用新值更新原有表行中的各列;

    • SET子句指示要修改哪些列和要给予哪些值;

    • WHERE子句指定应更新哪些行。如果没有WHERE子句,则更新所有的行;

    • 如果指定了ORDER BY子句,则按照被指定的顺序对行进行更新;

    • LIMIT子句用于给定一个限值,限制可以被更新的行的数目。

    mysql> select * from test;
    +----+----------+
    | id | name     |
    +----+----------+
    |  1 | zhangsan |
    |  3 | xiaoming |
    |  4 | lisi     |
    +----+----------+
    3 rows in set (0.00 sec)
    ​
    mysql> update test set name = "xiaohong" where id = 3;
    Query OK, 1 row affected (0.04 sec)
    Rows matched: 1  Changed: 1  Warnings: 0
    ​
    mysql> select * from test;
    +----+----------+
    | id | name     |
    +----+----------+
    |  1 | zhangsan |
    |  3 | xiaohong |
    |  4 | lisi     |
    +----+----------+
    3 rows in set (0.00 sec)
  9. 增加字段

    格式:ALTER TABLE tb_name ADD col_name1 column_definition [FIRST | AFTER col_name]; [FIRST | AFTER col_name] 指定位置关系,FIRST表示在第一列,AFTER col_name表示在 col_name 列之后;

    mysql> alter table test add column(
       -> phone INT(11) NULL,
       -> addr VARCHAR(50)
       -> );
    Query OK, 0 rows affected (0.32 sec)
    Records: 0  Duplicates: 0  Warnings: 0
    ​
    mysql> desc test;
    +-------+--------------+------+-----+---------+----------------+
    | Field | Type         | Null | Key | Default | Extra         |
    +-------+--------------+------+-----+---------+----------------+
    | id   | int(11)     | NO   | PRI | NULL   | auto_increment |
    | name  | varchar(255) | NO   |     | NULL   |               |
    | phone | int(11)     | YES  |     | NULL   |               |
    | addr  | varchar(50)  | YES  |     | NULL   |               |
    +-------+--------------+------+-----+---------+----------------+
    4 rows in set (0.00 sec)
  10. 删除列

    格式:ALTER TABLE tb_name DROP [COLUMN] col_name1 [, DROP col_name2 ...];

    • [COLUMN] 关键字可有可无;

    • 删除多列时需使用DROP关键字,不可直接用 , 分隔;

  11. 修改字段

    (1)修改列

    ALTER TABLE tb_name
    CHANGE [COLUMN] old_col_name new_col_name column_definition #注意一定要指定类型
    [FIRST|AFTER col_name];

    (2)修改列类型

    ALTER TABLE tb_name
    MODIFY col_name column_definition;
  12. 添加约束

    (1)添加主键约束

    格式:ALTER TABLE tb_name ADD [CONSTRAINT [symbol]] PRIMARY KEY index_type;

    • [CONSTRAINT [symbol]] constraint 关键字,symbol 表示约束别名,可有可无,mysql会自动创建;

    • [index_type] 索引类型 包含 {B+TREE | HASH},存储引擎为InnoDB时只能使用B+TREE,默认值为B+TREE,但是InnoDB可以有自适应hash索引、即索引中的索引;

    (2)添加唯一约束

    格式:ALTER TABLE tb_name ADD [CONSTRAINT [symbol]] UNIQUE [INDEX|KEY] [index_name] [index_type] (index_col_name,...);

    • [INDEX|KEY] 说明是 INDEX 还是 KEY,关于INDEX 和 KEY 的区别参考:Mysql中的key和index的区别

    • [index_name] 索引名称,好像 和[CONSTRAINT [symbol]] 没有区别;

    • [index_type] 索引类型, 包含 {BTREE | HASH}

    (3)删除约束

    格式:alter table tb_name drop key index_name;

  13. 添加索引

    (1)加索引

    格式:

    #普通索引
    ALTER TABLE tb_name
    ADD {INDEX|KEY} [index_name](key_part,...) [index_option] ...
    ​
    #全文索引
    ALTER TABLE tbl_name
    ADD FULLTEXT [INDEX|KEY] [index_name](key_part,...) [index_option] ...
    ​
    #空间索引
    ALTER TABLE tbl_name
    ADD SPATIAL [INDEX|KEY] [index_name](key_part,...) [index_option] ...
    ​
    key_part:
       col_name [(length)] [ASC|DESC]
    ​
    index_type:
        USING {BTREE|HASH}
    ​
    index_option:
       KEY_BLOCK_SIZE [=] value
      | index_type
      | WITH PARSER parser_name
      | COMMENT 'string'
posted @ 2020-03-01 19:44  NoviceLearning  阅读(746)  评论(0编辑  收藏  举报