Introduction to replacement technology of SAP ABAP CDs view view

stay ABAP Dictionary in , You can use it CDS The name of the entity will CDS Views are assigned to transparent database tables and classic database views as replacement objects . The premise is that CDS The structure type of view definition matches the structure of database table or classic view , As shown below :

• The number of two model fields must match
• Must be able to CDS A field of the view is assigned to the corresponding field of the database table or classic view
• about client For fields , Its mapping relationship is independent of its name . For all other components of the database table ,CDS There must be an element with the same name in the view
• Database tables and CDS The order of fields in the view does not need to match
• For all assigned fields , Technology type attribute , For example, built-in data types 、 Length and decimal places must match
• CDS The view cannot have input parameters
• Database views that are modifiable for maintenance status , It is impossible to define replacement objects and open table buffers at the same time .

If a database table or classic view is accessed , And a replacement object is assigned to this table or view in the following cases , The replacement object will be accessed , Instead of database tables or classic views :

• When ABAP SQL Of SELECT, FETCH perhaps OPEN SQL During the interview

Other write operations , Still applied to the original database table .

ABAP SQL It's using ABAP Statement implementation SQL General name of subset , Include DML part . So-called DML, yes Data Manipulation Language Abbreviation , Data operation language , yes SQL Subset .DML Statement to read and change the contents of relational database tables . stay ABAP in ,DML Yes, it is ABAP SQL It means .

ABAP SQL Statement uses ABAP SQL Interface to access AS ABAP database .ABAP SQL Can be used to read (SELECT) And modify (INSERT, UPDATE, modify, or DELETE) stay ABAP Dictionaries ( namely ABAP Thing code often used by developers SE11) Data in the database table defined in . With the help of ABAP SQL Interface ,ABAP Developers can directly access database tables 、 Views and all non Abstract CDS Entity .