Database Views - Overview

The following views are supported by SAP HANA:

• You can define view using SQL DDL statements
• You can define calculation views or more generally, information models using SAP HANA Tools.
• You can define views using Core Data Services and the HANA Development Perspective in SAP HANA Tools.

 

Database view: Advantages

• De-couple applications from the lower level

You can use the database view to change the conceptual schema without causing side effects on applications.

• Create a view tailored to the users and their needs

The application programmers do not have to know the full database structure but only the excerpt that is relevant to them.

• Simplify queries

Complex queries referencing views are easier to formulate, provided that the view provides an appropriate pre-selection of data.

• Limited access to data

You can use the view to realize value-dependent access privileges or to make sure certain columns are never visible for certain users.

 

 

Managing Database views

You can create database views using the CREATE VIEW statement as follows

CREATE VIEW <Name of the view> [ (<list of column names>)] AS 
SELECT ……

 

You can also use the following in the SELECT part of the CREATE VIEW statement:

• Calculation and functions
• Any type of join
• A TOP N clause to limit the number of rows returned
• DISTINCT
• Aggregate expressions, GROUP BY and HAVING clauses
• Subqueries, uncorrelated or correlated
• UNION
• An ORDER BY clause to achieve a default sort order of results.

 

 

 

Modifying Data with a View

 

 

 

You cannot modify data through a view if the view definition contains any of the following:

• A calculation or function in the projection list
• A subquery in the projection list
• DISTINCT
• The TOP N clause
• Aggregate expressions
• A GROUP BY clause
• UNION