sql views interview questions

Hi Devs, Today we are going to see what exactly is SQL views and why you should use them. SQL views are the virtual tables created by you when you define a command to create a view. You can do all normal operation such as create,update,delete on views. Views can be very useful if used correctly.

Lets see How to Create a View

// To create a view.

mysqli_query($conn, "CREATE VIEW userCustomList AS SELECT first_name as name, age as user_age FROM users");

Here we are creating a view which will hold data “name” and “user_age” only from the main table.

Update a SQL View Selection

Incase you want to update a view

// Updating View Selection

mysqli_query($conn, "CREATE OR REPLACE VIEW userCustomList AS 
    SELECT first_name as name, age as user_age, salary FROM users WHERE salary > 90000");

Here we are also getting “salary” and we are getting only those users where salary more than 90000.

Update a Record In View

// Simple query to update view

mysqli_query($conn, "UPDATE userCustomList SET name = 'Something'");

Note : Update and delete will also take effect in original table as well, So be very careful. And take backup of your data.

Deleting A View

// This will delete the view.

mysqli_query($conn, "DROP VIEW userCustomList");

Incase you want to delete data from view

Delete Data From View

// Deleting data from view

mysqli_query($conn, "DELETE FROM userCustomList");

Note : Update and delete will also take effect in original table as well, So be very careful. And take backup of your data.