MySQL学习总结(4)-表级操作语句

1.创建数据表

 语句:create table [if not exists] table_name(

        column_name data_type,

        ......

        );

2.查看数据表列表

 show tables [from db_name]

[like ‘pattern’ | where expr]

(1)查看当前数据表(已打开的)

(2)查看非当前数据表

3查看数据表的创建命令

4.查看数据表结构show columns from table_name;或desc table_name;

5.外键约束操作

foreign key(子表外键列字段名)references 父表名(参照列)

6.修改数据表语句

alter table table_name 修改操作1(添/删),修改操作2(添/删);

(1)添加单列

alter table table_name add [column] col_name col_definition [first | after col_name ];

字段位置:默认最后、first(最前)、after(col_name后)

(2)添加多列

alter table table_name add [column] (col_name col_definition,...);

(3)删除列

alter table table_name drop [column] col_name;

7.添加主键约束

alter table tbl_name add [constraint[symbol*约束标记*]] primary key[index_type](index_col_name);

8.添加唯一约束

alter table tbl_name add [constraint[symbol]] unique [index | key] [index_name] [index_type] (index_col_name,...);

9.添加外键约束

alter table tbl_name add [constraint[symbol]] foreign key [index_name] (index_col_name,...) reference_definition;

10.添加/删除默认约束

alter table tbl_name alter[column] col_name {set default literal | drop default};

11.删除主键约束

 alter table tbl_name drop primary key;

12.删除唯一约束

alter table tbl_name drop {index | key} index_name;

13.删除外键约束

alter table tbl_name drop foreign key fk_symbol;

查看表的创建命令,找到外键约束标记

14.修改列定义

alter table tbl_name modify[column]col_name col_definition [first | after col_name];

15.修改列名称

alter table tbl_name change[column]old_col_name new_col_name col_definition [first | after col_name]

change比modify功能多

16.数据表更名

方法1

alter table tbl_name rename [to | as] new_tbl_name

方法2

rename table tbl_name to new_tbl_name [,tbl_name2 to new_tbl_name2]...

17.连接(join)

(1)update tdb_goods inner join tdb_goods_cates on goods_cate=cate_name

set goods_cate=cate_id;

18.创建数据表同时将查询结果写入到数据表

create table [if not exists] tbl_name

[(create_definition,...)]

select_statement

19.字段名不明确处理

update tdb_goods as g inner join tdb_goods_brands as b on g.brand_name=b.brand_name

set g.brand_name=b.brand_id;

20.多表删除(Join作为筛选条件用于delete)

Delete tbl_name[.*] [,tbl_name[.*]]...

From table_references

[where where_condition]

21.修改存储引擎的方法

(1)通过修改mysql配置文件(my.ini)实现

default-storage-engine=engine_name

(2)通过创建数据表命令实现

create table table_name(

...

...

)engine [=] engine_name;

(3)通过修改数据表命令实现

alter table table_name engine [=] engine_name;

猜你喜欢

转载自blog.csdn.net/qq_38861828/article/details/85063332