ABAP dictionary object types

Though it is not Mandatory for a BASIS Consultant to know about ABAP Dictionary in depth, it is always help if we can hve knowledge about this.Here is the small introduction.

The ABAP dictionary can handle eight different object types

Table. As previously explained, a table is a two−dimensional data matrix. A table can contain zero or many rows, corresponding to the predefined table structure (entity type). This is, at the same time, a complex structure, which can be made up of one or several fields (attributes). Every row that makes up the database table has the same structure and properties. The fields that make up the structure of the table records, as well as its attributes, permitted value range, and so on, are set when defining the table.


Structures. The object structure refers to the definition of a compound object that does not have any content. It's like a table or a view, but it never has entries: it's only a structure. These types of objects are used in programs for defining data structures or for defining data in the interfaces from the module pools and the screens. The basic difference between structures and tables (or views) is that the structure does not exist at the underlying database system level; however, both tables and views do exist in the database. Structures only exist as definitions in the dictionary. As a result, structures do not need to be activated.


Views. From the relational database point of view, a view is a virtual table. It contains data which are really stored in other tables. The contents for the views are dynamically generated when called from a program or a transaction. In the simplest form, the fields within a view all come from a single table, where you could select all of them or just a few (projections), or select some of the fields of the table according to specific criteria (selection) using the Select option. Other, more complex forms of views allow for selecting fields from different tables which are related by foreign keys (join operation). You can also use the three methods combined for creating a view: projection, selection, and join.


Data elements. They are a semantic definition of the properties and type for a table field. It's an intermediate object between the object type domain and the table field. A field in R/3 is always associated with a data element, which at the same time is always related to a domain. Some properties of table fields in the SAP environment can only be defined at the data element level, for example, the text elements associated with the fields. As an example, suppose there is a table with the fields manager_name and employee_name. These fields could have the same technical description−they could be strings with 30 characters−char (30). They would be, however, different at the semantic level: the meaning is different, since they relate to names of people at different levels in company. This difference is only reflected with the text elements associated to the data elements, but it is also useful for the online help which can be associated with the fields.


Domains. They are the formal definition of the data type from a technical and syntactical point of view. They set attributes including data type, length, possible value ranges, and so on.


Lock objects. These types of object are used for locking and synchronizing the access to database records in tables. This mechanism is used to enforce data integrity, that is, two users cannot update the same data at the same time. The lock object definition includes the table or tables which can be concurrently accessed, as well as the key fields for the access. A lock object request is not only used to lock a single record from a table but also to lock a complete logical object. Defining a lock object in the data dictionary automatically generates two ABAP function modules which allows for locking (ENQUEUE) and unlocking (DEQUEUE) the object.



Search helps. These are objects that can be used for assigning input help (using the F4 function key) to fields. These types of objects are new with release 4.0 and are meant to replace the functionality of matchcodes. The main difference between search helps and matchcodes is that search helps are physically built based on transparent tables. There are two types of search helps: collective and elementary.


Type group. These objects contain ABAP type definitions. From version 3.0 onward, developers can define their own data types based on standard R/3 data types.


Development classes are logical groups of development objects which are related, normally deployed for the same application module, related reports, and so on. Development classes are particularly important for team development, the transport system, and use within the repository browser, application hierarchy, and so forth.