ABAP join syntax is available for transparent tables and IDocs on SAP 4.x systems. When you have multiple sources connected to the same Application Source Qualifier, the ABAP program can select the tables using ABAP join syntax. ABAP join syntax uses an INNER JOIN or an OUTER JOIN statement to select multiple source tables. ABAP join syntax extracts data directly from the tables on the database server.
To use ABAP join syntax to generate the ABAP program, clear both the Force Nested Loop option and the Exec SQL option in the Application Source Qualifier transformation.