DDL basic operation

title ：

（1） Create database , Delete database , View the database and all tables in the database , Select the database table and select all

（2） Create database tables

One , database

1, Create database

create database [if not exists] database-name
// Brackets indicate whether to add or not 

2, Delete database

drop database database_name

3, View the database and all tables in the database

// view the database 
show database
// View all tables in the current database 
show tables

4, Select database

use databas

Two , Create database tables

create table table_name(
    column_name data_type[not null][default default_value][auto_increment][],
    ...
    [primary key(pk_name),]
    [foreign key(fk_name) references referenced_table_name(ref_pk_name)]
)
/* Syntax description 
table_name: Table name 
column_name: Field name 
data_type: Field data type 
default_value: The default value is 
auto_increment: Primary key auto growth 
pk_name: The primary key name in the current table 
fk_name: Key names in the current table 
referenced_table_name: The application shows that （ Primary key name ）
ref_pk_name: The name of the main key of the applied table */