Summary of alter operation in SQL

alter Usage Summary

1、 Add column

alter table  Table name  add column  Name   type  ‘ describe ’

2、 Delete column

alter table  Table name  drop column  Column name to delete 

3、 Modify column type 、 length

ALTER TABLE  Table name  CHANGE COLUMN  Name   New column names   new property 
 or 
alter table  Table name   modify column  Name   attribute (col-type);

4、 To be ranked high

ALTER TABLE  Table name  CHANGE COLUMN  Name   New column names   attribute 

5、 rename table

ALTER TABLE  Table name  RENAME TO  Table new name 

6、 Delete the primary key in the table

Alter TABLE  Table name  DROP primary key

7、 Add primary key

ALTER TABLE  Table name  ADD CONSTRAINT  Constraint name  PRIMARY KEY ( Add columns )

8、 Add index

ALTER TABLE  Table name  ADD index  Index name  ( Name );

9、 Modify column properties

ALTER TABLE  Table name  MODIFY COLUMN  The column name of the attribute to modify   new property ;

reference ：
https://blog.csdn.net/qq_41820897/article/details/100179834