Basic operation of tables in MySQL

basic creation of a table

    create TABLE userinfo (
        username char (5) Not NULL,
         pwd VARCHAR (
         age

Sex SMALLINT(100)
)

The blue representation is the keyword in SQL CREATE TABLE userinfo is the table name and the field is created in such a way as username CHAR(5), c11>username The data type of the field that represents the second bit after the field name is the field length in parentheses, not NULL

Renaming a table

RENAME TABLE ' user ' to NewUser

Change the user table to be named NewUser table

Deletion of tables

DROP TABLE newuser

Remove the name of the user table from the database

Add a new field to the table

ALTER TABLE userinfo ADD Hobby char (a) not NULL

Add a userinfo table with a new field for hobby and also set the type of the data

Renaming columns in a table

ALTER TABLE UserInfo Change username newname VARCHAR (+)

Update the username field named UserInfo table to the new field name for NewName and specify the data type of the field

Basic operation of tables in MySQL