MySQL To strengthen


Not null


Primary key

Zerofill primary key auto_increment

primary key auto_increment

constraint Main table _ Side table _pk foreign key (id) reference Main table (id);

constraint Main table _ Side table _pk foreign key (id) reference Main table (id)on update cascade on delete cascade Cascade modification cascading deletion


create procedure




First normal form Each field is indivisible

Second normal form Each field has a dependency on the primary key

Third normal form In addition to the primary key, they are directly dependent on the primary key

Internal connection :

Select * from a,b where =

Select * from a where inner join b on =

The left outer join 、 Right connection

Select * from a left outer join b on =

-- Use the left table as the main table To display   Can show null

Call Stored procedure name – call

See all global variables show variables

Look at a global variable show @@ Variable name

Modify global variables   set Variable name = value

Session variables set @ Variable name = value

View session variables select @ Variable name

Create trigger tri_ name after update on Table name for each row

Insert into Record sheet values(‘ Content ’);

-- Change Password

Update user set password = password(‘ New password ’) where user=’ user ’

-- Assign permissions

Grant select on database . Table name to ‘ user ’@‘localhost’identified by ‘ password ’;

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