MySQL Basics (ii)

First, the View

A view is a virtual table (not a real one), which is the essence of getting dynamic datasets and naming them based on SQL statements. Users can only use "name" to get a result set and use it as a table.

Select *  from (Selectfromwhere course_id=3)  as  where>

temporary table Search

1. Create a View

-- Syntax: --         CREATE VIEW name SQL statement createviewasselect from where course_id=3

Create an instance

2. Delete View

-- Syntax: --         frop View name dropView v1

Delete View V1

3. Modify the View

-- Syntax: --         ALTER VIEW name as SQL statement alterviewasselectfrom where course_id =1  

Modify View v1

4. Using views

When you use a view, you manipulate it as a table, and because the view is a virtual table, you cannot use it to create, update, and delete real tables, only for queries.

Select *  from V1

working with views v1Second, Trigger

Before and after an "Add/delete/change" operation on a table you can use triggers when you want to trigger a particular behavior, which is used to customize the behavior of the user before and after the "Add/delete/change" row of the table.

1. Create basic syntax

MySQL Basics (ii)