MySQL基本简单操作02

Posted 2020-12-04 顾北清

mysql基本简单操作

先进入Mysql容器。

[[email protected] ~]# docker exec -it mysql /bin/bash
[email protected]:/# mysql -uroot -p000000
mysql: [Warning] Using a password on the command line interface can be insecure.
Welcome to the MySQL monitor.  Commands end with ; or g.
Your MySQL connection id is 8
Server version: 8.0.11 MySQL Community Server - GPL

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Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.

Type 'help;' or 'h' for help. Type 'c' to clear the current input statement.

mysql>

新建一个数据库。

mysql> create database gubeiqing;
Query OK, 1 row affected (0.02 sec)

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| gubeiqing          |
| information_schema |
| mysql              |
| performance_schema |
| sys                |
+--------------------+
5 rows in set (0.01 sec)

进入数据库，新建数据表。

mysql> use gubeiqing;
Database changed
mysql> show tables;
Empty set (0.00 sec)

mysql> create table gubeiqing_table(name varchar(20) not null , age varchar(20) not null);
Query OK, 0 rows affected (0.11 sec)

mysql> show tables;
+---------------------+
| Tables_in_gubeiqing |
+---------------------+
| gubeiqing_table     |
+---------------------+
1 row in set (0.01 sec)

接着给数据库新增列，基本简单语法是：ALTER TABLE 表名 add column 列名 列类型 是否为空;。

mysql> desc gubeiqing_table;
+-------+-------------+------+-----+---------+-------+
| Field | Type        | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| name  | varchar(20) | NO   |     | NULL    |       |
| age   | varchar(20) | NO   |     | NULL    |       |
+-------+-------------+------+-----+---------+-------+
2 rows in set (0.01 sec)

mysql> alter table gubeiqing_table add column job varchar(20) not null;
Query OK, 0 rows affected (0.26 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> desc gubeiqing_table;
+-------+-------------+------+-----+---------+-------+
| Field | Type        | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| name  | varchar(20) | NO   |     | NULL    |       |
| age   | varchar(20) | NO   |     | NULL    |       |
| job   | varchar(20) | NO   |     | NULL    |       |
+-------+-------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

修改列名，基本简单语法是：ALTER TABLE 表名 change column 原列名 修改后的列名 列类型 是否为空；。

mysql> desc gubeiqing_table;
+-------+-------------+------+-----+---------+-------+
| Field | Type        | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| name  | varchar(20) | NO   |     | NULL    |       |
| age   | varchar(20) | NO   |     | NULL    |       |
| job   | varchar(20) | NO   |     | NULL    |       |
+-------+-------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

mysql> alter table gubeiqing_table change column job gbq_job varchar(20) not null;
Query OK, 0 rows affected (0.11 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> desc gubeiqing_table;
+---------+-------------+------+-----+---------+-------+
| Field   | Type        | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+-------+
| name    | varchar(20) | NO   |     | NULL    |       |
| age     | varchar(20) | NO   |     | NULL    |       |
| gbq_job | varchar(20) | NO   |     | NULL    |       |
+---------+-------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

删除刚刚新增的列，基本简单语法是：ALTER TABLE 表名 drop column 列名;。

mysql> desc gubeiqing_table;
+---------+-------------+------+-----+---------+-------+
| Field   | Type        | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+-------+
| name    | varchar(20) | NO   |     | NULL    |       |
| age     | varchar(20) | NO   |     | NULL    |       |
| gbq_job | varchar(20) | NO   |     | NULL    |       |
+---------+-------------+------+-----+---------+-------+
3 rows in set (0.00 sec)

mysql> alter table gubeiqing_table drop column gbq_job;
Query OK, 0 rows affected (0.11 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> desc gubeiqing_table;
+-------+-------------+------+-----+---------+-------+
| Field | Type        | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| name  | varchar(20) | NO   |     | NULL    |       |
| age   | varchar(20) | NO   |     | NULL    |       |
+-------+-------------+------+-----+---------+-------+
2 rows in set (0.00 sec)

然后说一下模糊搜索，就比如现在要在数据库里查找zhangsan的信息，可是只记得zhang剩下的部分都不记得了，那么就可以使用模糊搜索，基本简单语法是：SELECT * from 表名 WHERE 字段 LIKE ‘模糊字段‘;。

mysql> select * from gubeiqing_table where name like 'zhang%';
+----------+-----+
| name     | age |
+----------+-----+
| zhangsan | 20  |
+----------+-----+
1 row in set (0.01 sec)

%用来表示不记得的部分，是通配符。
除了%之外还有 _表示任何单个字符，[ ]指定范围或集合中的任何单个字符，[^]不属于指定范围或集合的任何单个字符。