CRUD operation of MySQL table structure

Create table

create table 表名(
    列名 列的类型(长度) 约束;
    列名2 列的类型(长度) 约束
);

Take any column name ;
column type:

java	sql
int	int()
char/string	char()/varchar() char (fixed length), varchar (variable length)
double	double()
float	float()
boolean	N/A
date	date():YYYY-MM-DD
	time():hh:mm:ss
	datetime():YYYY-MM-DD hh:mm:ss default value is null
	timestamp():YYYY-MM-DD hh:mm:ss uses the current time by default
	text is mainly used to store text
	blob: Stored in binary

Column constraints:

• Primary key constraint: primary key (pk_xxx)
• Unique constraint: unique (uq_xxx)
• Non-empty constraint: not null
• Foreign key constraint: foreign key (fk_xxx)
• Conditional constraints: check (chk_xxx)
• Default constraint: default (df_xxx)

Create table:
1. Analyze entity: student

create table student(
 sid int primary key,
 sname varchar(6),
 sex char(1),
 age int
);

View all tables:

show tables;

View the definition of the table:

show create table 表名;
如:show create table day06;

View table structure:

desc 表名;
如:desc student;

Modify the table:
add column (add), modify column (modify), modify column name (change), delete column (drop), modify table name (remane), modify table character set (default character)

添加列(add):
alter table 表名 add 列名 列的类型 列的约束;
如:alter table student add changji int not null;

修改列(modify):
alter table 表名 modify 列名 新列的类型 列的约束;
如:alter table student modify ssex varchar(2);

修改列名(change):
alter table 表名 change 旧列名 新列名 列的类型 列的约束;
如:alter table student change ssex gender varchar(2);

删除列(drop):
alter table 表名 drop 列名;
如:alter table student drop chengji;

修改表名(remane):
rename table 旧表名 to 新表名;
如:rename table student to heima;

修改表的字符集(default character):
alter table 表名 character set 新字符集;
如:alter table student character set gbk;

Delete table:

drop table 表名;
如:drop table heima;