Modify table structure

1, Basics

alter table table_name  Modify clause 
// It is allowed to specify multiple actions , Comma off 

2, Modify clause

newly added

add column_name data_type [not null][default default_value]


// Primary key 
add primary key
drop primary key

change

change column_name new_column data_type
[not null][default default_name]

to update

modify column_name new_data_type[not null][default default_value]
// Directly change without entering the old name, directly enter the new name 

Delete field

drop column column_name

Delete unique constraint

drop column column_name

rename table

rename table table_name to new_table_name