MySQL basic (DDL)

MySQL basic (DDL)
SQL Classification

        SQL statements can be divided into three categories.

DDL: Data Definition Language, defining data segments, databases, data tables, and other DML: data manipulation statements, used to add, delete, update, and query database records DCL: Data Control statements, statements used to control the direct permission and access level of different data segments

Prepare, first start MySQL Service net start mysql, and enter mysql, mysql-u root-p (-u is followed by the database user,-p indicates that the password needs to be entered)

1. DDL statements

Language used to create, delete, and modify objects in the database.

1.1 create database ----;

After creating the database, view the database show databases;

Select the database use ---
View the table show tables in the database;

1.2 delete a database

Drop database ----;

1.3 create a table

Create table --- (name1 type constraint, name2 type constraint ......);
Check the created table to see if it meets the requirements of desc --;

1.4 delete a table

Drop table ----;

1.5 modify a table

Alter table --- modify ---;

Add the new field alter table --- add colum ----;

Delete field alter table --- drop colum ---;
Alter table --- change ---;