數據庫基本語法：
DDL：Data Defination Lanuage: 數據定義語言
    CREATE, ALTER, DROP
DML：Data Manapulate Language: 數據操作語言
    INSERT, REPLACE, UPDATE, DELETE
DCL：Data Control Language: 數據控制語言
    GRANT, REVOKE
常用命令：
mysql命令不區分大小寫 這些是基本常識
DDL 
    CREATE
    ALTER
    DROP
DML 操縱語言
    INSERT
    UPDATE
    DELETE
DCL 控制語言
    GRANT
    REVOKE
第一篇 DDL 庫和表 create alter drop
mysql> create database mydb;
Query OK, 1 row affected (0.01 sec)
mysql> use mydb;
Database changed
mysql> show tables;
Empty set (0.00 sec)
mysql> create table students (id char(20),name char(20),age char(10),score char(10)); 建表並添加4個字段和字段的類型
Query OK, 0 rows affected (0.10 sec)
mysql> show tables;
+----------------+
| Tables_in_mydb |
+----------------+
| students       |
+----------------+
1 row in set (0.00 sec)
mysql> create table teachers as select * from students; 建立教師表，字段同學生表
Query OK, 0 rows affected (0.02 sec) 
Records: 0  Duplicates: 0  Warnings: 0
mysql> show tables;
+----------------+
| Tables_in_mydb |
+----------------+
| students       |
| teachers       |
+----------------+
2 rows in set (0.00 sec)
mysql> desc students;
mysql> desc teachers;
+-------+----------+------+-----+---------+-------+
| Field | Type     | Null | Key | Default | Extra |
+-------+----------+------+-----+---------+-------+
| id    | char(20) | YES  |     | NULL    |       |
| name  | char(20) | YES  |     | NULL    |       |
| age   | char(10) | YES  |     | NULL    |       |
| score | char(10) | YES  |     | NULL    |       |
+-------+----------+------+-----+---------+-------+
mysql> alter table teachers add subject varchar(100); 添加字段
Query OK, 0 rows affected (0.06 sec)
Records: 0  Duplicates: 0  Warnings: 0
mysql> desc teachers;
+---------+--------------+------+-----+---------+-------+
| Field   | Type         | Null | Key | Default | Extra |
+---------+--------------+------+-----+---------+-------+
| id      | char(20)     | YES  |     | NULL    |       |
| name    | char(20)     | YES  |     | NULL    |       |
| age     | char(10)     | YES  |     | NULL    |       |
| score   | char(10)     | YES  |     | NULL    |       |
| subject | varchar(100) | YES  |     | NULL    |       |
+---------+--------------+------+-----+---------+-------+
mysql> alter table teachers drop score; 刪除字段
Query OK, 0 rows affected (0.05 sec)
Records: 0  Duplicates: 0  Warnings: 0
mysql> desc teachers;
+---------+--------------+------+-----+---------+-------+
| Field   | Type         | Null | Key | Default | Extra |
+---------+--------------+------+-----+---------+-------+
| id      | char(20)     | YES  |     | NULL    |       |
| name    | char(20)     | YES  |     | NULL    |       |
| age     | char(10)     | YES  |     | NULL    |       |
| subject | varchar(100) | YES  |     | NULL    |       |
+---------+--------------+------+-----+---------+-------+
mysql> alter table teachers change id teacherid char(30); 修改字段名，用change
Query OK, 0 rows affected (0.06 sec)
Records: 0  Duplicates: 0  Warnings: 0
mysql> desc teachers;
+-----------+--------------+------+-----+---------+-------+
| Field     | Type         | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+-------+
| teacherid | char(30)     | YES  |     | NULL    |       |
| name      | char(20)     | YES  |     | NULL    |       |
| age       | char(10)     | YES  |     | NULL    |       |
| subject   | varchar(100) | YES  |     | NULL    |       |
+-----------+--------------+------+-----+---------+-------+
mysql> alter table teachers modify teacherid varchar(5); 修改字段屬性，用modify
Query OK, 0 rows affected (0.02 sec)
Records: 0  Duplicates: 0  Warnings: 0
mysql> desc teachers;
+-----------+--------------+------+-----+---------+-------+
| Field     | Type         | Null | Key | Default | Extra |
+-----------+--------------+------+-----+---------+-------+
| teacherid | varchar(5)   | YES  |     | NULL    |       |
| name      | char(20)     | YES  |     | NULL    |       |
| age       | char(10)     | YES  |     | NULL    |       |
| subject   | varchar(100) | YES  |     | NULL    |       |
+-----------+--------------+------+-----+---------+-------+
mysql> drop table teachers; 刪除表，drop table table_name
Query OK, 0 rows affected (0.00 sec)
總結1：
    查看庫中的表：SHOW TABLES FROM db_name；
    查看表的結構：DESC tb_name;
    刪除表：DROP TABLE tb_name；
修改表：
    ALTER TABLE tb_name
        MODIFY 改字段屬性
        CHANGE 改字段名稱
        ADD 添加字段
        DROP 刪除字段
help create table獲取幫助 help alter table
第二篇 DML 數據修改 insert update delete ; select
mysql> insert into students (id,name,age,score) value(‘1‘,‘wxtan‘,‘18‘,‘99‘),(‘2‘,‘yull‘,‘17‘,‘80‘);  增加表內數據，insert into
Query OK, 2 rows affected (0.00 sec)
Records: 2  Duplicates: 0  Warnings: 0
mysql> select * from students;
+------+-------+------+-------+
| id   | name  | age  | score |
+------+-------+------+-------+
| 1    | wxtan | 18   | 99    |
| 2    | yull  | 17   | 80    |
+------+-------+------+-------+
mysql> insert into students value(‘3‘,‘AA‘,‘30‘,‘60‘);  （如果全部字段都添加可以不用寫）
Query OK, 1 row affected (0.00 sec)
mysql> select * from students;
+------+-------+------+-------+
| id   | name  | age  | score |
+------+-------+------+-------+
| 1    | wxtan | 18   | 99    |
| 2    | yull  | 17   | 80    |
| 3    | AA    | 30   | 60    |
+------+-------+------+-------+
mysql> update students set age=14 where id=1; 修改表內數據，update table_name
Query OK, 1 row affected (0.01 sec)
Rows matched: 1  Changed: 1  Warnings: 0
mysql> select * from students;
+------+-------+------+-------+
| id   | name  | age  | score |
+------+-------+------+-------+
| 1    | wxtan | 14   | 99    |
| 2    | yull  | 17   | 80    |
| 3    | AA    | 30   | 60    |
+------+-------+------+-------+
3 rows in set (0.00 sec)
mysql> update students set age=‘28‘ where name=‘yull‘; 修改表內數據，update table_name
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0
mysql> select * from students;
+------+-------+------+-------+
| id   | name  | age  | score |
+------+-------+------+-------+
| 1    | wxtan | 14   | 99    |
| 2    | yull  | 28   | 80    |
| 3    | AA    | 30   | 60    |
+------+-------+------+-------+
3 rows in set (0.00 sec)
mysql> select * from students;
+------+-------+------+-------+
| id   | name  | age  | score |
+------+-------+------+-------+
| 1    | wxtan | 14   | 99    |
| 2    | yull  | 28   | 80    |
| 5    | bb    | 44   | 55    |
| 6    | cc    | 44   | 60    |
+------+-------+------+-------+
4 rows in set (0.00 sec)
mysql> delete from students where age=‘44‘; 刪除表內數據，delete from
Query OK, 2 rows affected (0.00 sec)
mysql> select * from students;
+------+-------+------+-------+
| id   | name  | age  | score |
+------+-------+------+-------+
| 1    | wxtan | 14   | 99    |
| 2    | yull  | 28   | 80    |
+------+-------+------+-------+
mysql> delete from students where age=‘14‘ or score=‘80‘; 可以用or and等條件表達式
Query OK, 2 rows affected (0.00 sec)
mysql> select * from students;
Empty set (0.00 sec)
mysql> select * from students; 數據查詢，select from
+------+--------+------+-------+
| id   | name   | age  | score |
+------+--------+------+-------+
| 1    | apple  | 20   | 88    |
| 3    | xigua  | 10   | 50    |
| 2    | banana | 30   | 68    |
+------+--------+------+-------+
3 rows in set (0.00 sec)
mysql> select id,name from students;
+------+--------+
| id   | name   |
+------+--------+
| 1    | apple  |
| 3    | xigua  |
| 2    | banana |
+------+--------+
3 rows in set (0.00 sec)
mysql> select id,name from students where age=20;
+------+-------+
| id   | name  |
+------+-------+
| 1    | apple |
+------+-------+
1 row in set (0.00 sec)
第三篇 DCL 權限 grant revoke；show grants for
mysql> grant select,insert,update on mydb.students to [email protected]