SQL CREATE VIEW

A SQL view is a virtual table and the SQL CRERATE VIEW statement is the SQL command that adds a new view to a SQL database.

A view can be accessed using the SQL SELECT statement like a table. A view is built by selecting data from one or more tables.

SQL views are used because they can provide the following benefits / functions:

• Database queries are simplified
• Database complexity is hidden
• Flexibility is increased - queries of views may not change when underlying tables chagne
• Security is increased - sensitive information can be excluded from a view

The SQL CREATE VIEW command is used as follows.

SQL CREATE VIEW Statement Syntax

CREATE VIEW <view_name> ( <column_name1>, <column_name2> ) AS <sql_select_statement>

The number of characters that can make up SQL names for tables, columns and views varies by DBMS. In many cases the limit is 30 characters. The leading character of the name must be alphabetic - not a number or special character. The name of a new view can not duplicate the name of an existing view or table and should not be the same as a SQL reserved word. The underscore character can be used to improve readability. List elements are seperated by commas.

SQL CREATE VIEW Statement Example - Data Filtering

The following example creates a view named V_TOP_CUSTOMER on table CUSTOMER with the following columns:

• customer_id
• customer_name
• ytd_sales_amt
• zip_code

Here are the contents of the table:

Column Name	Datatype	Nullability
customer_id	INT	NOT NULL
customer_name	VARCHAR(20)	NOT NULL
ytd_sales_amt	MONEY	NOT NULL
line_1_addr	VARCHAR(50)	NULL
city_name	VARCHAR(50)	NOT NULL
state_code	CHAR(2)	NOT NULL
zip_code	CHAR(9)	NOT NULL

This SQL CREATE VIEW Statement is executed:

CREATE VIEW V_TOP_CUSTOMER ( customer_id, customer_name, ytd_sales_amt, zip_code) AS SELECT customer_id, customer_name, ytd_sales_amt, zip_code FROM CUSTOMER WHERE ytd_sales_amt > 1200.00