SQL Programming language and SQL Database engines provide some useful mechanisms in order to make management of the data easier. SQL View
is one of them which can be used to create a table from a SQL result set.
What Is SQL View?
SQL View is a virtual table which does not exist in a database physically. SQL View table is created from an SQL statement which is generally a select result set. View have rows, columns just like a regular table. The fields are generally related with one or more fields from real tables in the database.
Syntax
The syntax of the SQL View is simple and like a SELECT
statement. We will use Create View
with view name and As
statement like below. The Select
statement will bind related rows, columns and fields to the SQL View
table. We can also use conditional statements like Where
etc.
Create View VIEWNAME AS Select column1, column2, … From TABLENAME Where CONDITION;
- `VIEWNAME` is the name of the view we will create
- `column1`, `column2` etc are columns we will use in view from `TABLENAME`
- `TABLENAME` is the table name we want to feed our view. Provided columns will be selected from this table.
- `CONDITION` is optional with `Where` statement.
Create SQL View
We will start with a simple SQL View creation. We will create a view named TurkishCustomers
from the table named Customers
and use CustomerName
and Contact
columns from this Customers
table.
Create View TurkishCustomers AS Select Name, Contact From Customers Where Country="Turkey";
Using SQL View
We have created the SQL View successfully. We can use it as a regular table. In this example, we will use Select
statement by providing the SQL View name as a table name which is TurkishCustomers
in this example.
Select * From TurkishCustomers;
Update SQL View
In some cases, the SQL View may have some changes. But as we use the View in a lot of SQL queries we just need to update the SQL View content like fields or conditions. We can use Create Or Replace View
statement. This statement will update the SQL View if it exists, if not the SQL View will be created from scratch.
In this example, we will update SQL View named TurkishCustomers
.
Create Or Replace View TurkishCustomers AS Select Name, Contact From AllCustomers Where Country="Turkey";
Drop or Remove SQL View
If we do not need the SQL View nay we can delete it with Drop View
statement. This can be useful if we will use the view name as a regular table. In this example we will delete or drop the SQL View TurkishCustomers
.
Drop View TurkishCustomers;