Structures

• Structures are combination of  different variables or types.
• Structures are defined in the same way as tables. However, a structure does not correspond to an object in the database. A structure can be used as a reference in ABAP/4 programs.
• Structures are defined and activated in the ABAP/4 Dictionary. They can than respond to ABAP/4 programs like tables in the TABLES instructions.
• In transparent tables, data can be saved in the database, but structures only contain data temporarily during the run-time of a program.
• Since structures that are used more than once are defined centrally, they can also be changed centrally. These changes are then effected at all relevant points by the active ABAP/4 Dictionary.
• In the ABAP/4 Dictionary, the information about a table is divided between domains, data elements and the table definition. The run-time object (nametab) collects this information in a table in a form, which is optional for application program access.
• The database utility allows you to create and delete objects defined in the ABAP/4 Dictionary in the database. In addition the database utility supports structural adjustments - so-called conversions - of an object definition in the database to changed definitions of the object in the ABAP/4 Dictionary. The operations, which the database utility executes for an object, are logged. The object log can be displayed from the database utility.

• There are 3 types of structures.

1. Flat Structure.
2. Nested Structure.
3. Deep Structure.

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