"Database" MySQL database (v)

A. DCL statement

1. Add Permissions:

1 Grant Select,insert on Sakila. *  to ' Z1 '@'localhost'by'123' ; 2 Note: Sakili is the database name, Z1 is the newly created database user, and 123 is the password

Database Add Permissions

2. Permission to recover:

1 Revoke Insert  on Sakila. *  from ' Z1 '@'localhost';

Permission Recall

Second, foreign key

1. The index type of the foreign key:

(1) RESTRICT: The parent table cannot be updated if the child table is associated with a record.

(2) No ACTION: restricts the parent table from being updated if the child table is associated with a record.

(3) CASCADE: The parent table updates or deletes the corresponding record of the child table when it is updated or deleted.

(4) Set null: The corresponding field of the child table is set NULL when the parent table is updated or deleted.

"Database" MySQL database (v)