Different types of Views in ABAP Dictionary

What is View?

Database Table has physically contains the data but view does not contain any physical data .
View is the joining of 1 or more database tables ,but view will pick the data from the database tables and project the data on the screen.

There are 4 types of views in the Data dictionary.

1) Database view
2) Mantaince view
3) Projection view
4) Help View


Database view:

• Database views implement the inner join.
• We can define the selection conditions in the view
• We can join 1 or multiple tables in the database view
• Foreign key relationship is not required between the tables for joining the tables
• If database view contains one table, we can read and write the data to the view
• If database view contains multiple tables, we can only read the data.
• We can access the database view from the program with Open and native SQl statments

Maintanance view:

• Mantainance views implement the outer join.
• We can define the selection conditions in the view
• We can join 1 or multiple tables in the maintanance view
• Foreign key relationship is  required between the tables for joining the tables
• If maintanance view contains one or multiple table, we can read and write the data to the view
• We can not access the maintance view from the program.We can maintain the data from the SM30 transaction

Projection view:

• A projection view contains exactly one table. You cannot define selection conditions for projection views.
• Projection views are used to hide fields of a table.
• It is also possible to access pooled tables or cluster tables with a projection view.
• We can access the projection view from the program with Open SQL statement.

Help view:

• Help views implement the outer join.
• We can define the selection conditions in the view
• We can join 1 or multiple tables in the help view
• Foreign key relationship is required between the tables for joining the tables
• If we need a view with outer join for the data selection in the search help, we have to use a help view as selection method.

 Inner join and Outer join example: