Translation: Logical Database (1): composition

The SAP standard program was debugged with a logical database-related section, which, by the way, translated the official help file of ABAP as an exercise. Please correct me.

Logical Database

A logical Database is a special development object that is edited in logical Database Builder and is available through a hierarchical tree structure (hierarchical structure) provide data for other ABAP programs. The most common purpose of a logical database is to release data from a database table, although other applications can do the same.

By using foreign key relationships, the logical database provides a hierarchical view of the cross-database tables. If the parts of these relationships make up the class tree hierarchy (tree-like hierarchical structures), the logical database can read data from the database tables of the components of those structures. In traditional ABAP, logical databases are typically used for these hierarchies based on the principles of input, processing, and output. The records of the actual database are then wrapped by the logical database. The logical database reads the data, places it in the program for local storage (if necessary), and passes it to an interface workspace (interface work area) line by line.

A logical database can be used to reuse a predefined method of reading data from a database table, or it can be used to implement further core tasks, such as defining a unified selection screen, a central permission check, or a centralized enhancement of performance.

Key features of the logical database include:

• Hierarchical structure

The structure defines the data view of the logical database. He usually inherits the logical database hierarchy defined by the foreign key relationship and controls the order in which the application transmits the data. In this way, the structure determines how other self-objects are constructed and their run-time behavior.

• Selections that can be used as a standalone standard selection screen

Selections defines a standard selection screen that can be used as a user interface for using a logical database. The appearance of the screen is defined by the structure by default. Selections can be modified and enhanced according to the needs of the user.

• Database programs written using ABAP

The database program contains the ABAP statements that are used to read data and transfer data to the application. It is basically a container for a special subroutine that contains a function of the logical database implementation. The report processor (reporting processor) of the runtime Environment (runtime Environment) calls these subroutines in the order defined by the structure. The database program is defined by the structure, and selections can be modified or enhanced to meet the needs of the user.

• More elements that can be added to a function

When an executable program is created, it can be assigned a logical database by logical the DB property. This allows the standard selection screen and program flow to be combined by selecting screens and logical database streams.

In addition, the logical database can call the function module ldb_process. This function module can be used to invoke multiple logical databases from a single program and nest as needed. A logical database can also be called multiple times in the same program, if it is programmed in the appropriate way.

Note:

When you create a logical database in logical, you should keep the following order, because it makes it easier for components that have already been created to generate recommendations for components that have not yet been created. Some of the most important properties of a logical database are created with its structure. Once the structure is defined, a recommendation is created by the selection include. This structure and selection include a template that is used to generate a logical database program. These components can then be quickly used to create a logical database of ready states, based on which further requirements can be implemented.

1. Builds a structure based on the root node.
2. Make it associated with a search help.
3. Generate and edit selection include.
4. Build and edit the logical database.
5. Further edits to other elements.

English Original:

A logical database is a special development object it is edited in logical database Builder and which provides other ABA P programs with data from the nodes of a hierarchical tree structure. The most common purpose of logical databases was to extract data from database tables, however other applications are Feasi ble.

Logical databases provide a hierarchical view across database tables associated using foreign key relationships. If parts of these relationships construct tree-like hierarchical structures, logical databases can read data from database Tables that is the components of these structures. In classic ABAP, logical databases is usually used in these hierarchical structures in accordance with the principle of I Nput, processing, and output. The actual database reads is then wrapped in the logical database. The logical database reads the data, saves it locally in the program (if necessary) and passes it row by row to an Interfa Ce work area.

As well as reusing predefined functions for reading data from database tables, logical databases can is implemented for FU Rther central tasks, such as defining uniform selection screens, central authorization checks, or making centralized Enhan Cements to performance.

The main features of a logical database is

A hierarchical structure
The structure defines the data view of the logical database. It generally inherits the given hierarchy of database tables defined by foreign key relationships and controls the order I n which the data is passed to the application program. The structure determines how the other subobjects is constructed and the runtime behavior.
Selections as a standalone standard selection screen
The selections define a standard selection screens to being used as a user interface for programs so use the logical databas E. The appearance of the defined by the structure by default. The selections can modified and enhanced to meet the requirements of the user.
A database program written in ABAP
The database program contains the ABAP statements for reading, the data and passing it to a application program. It is basically a container for special subroutines in which the functions of the logical database is implemented. The reporting processor of the runtime environment calls these subroutines in the order defined by the structure. The database program was defined by the structure and the selections and can be modified or enhanced to meet the Requiremen TS of the user.
Further elements, which add to the functions.
When an executable program was created, it can be assigned to a logical database using the logical database attribute. This allows, the standard selection, and the program flow to being combined with the selection screen and flow of the LO Gical database.

Furthermore, logical databases can call the function module ldb_process. This function module can is used to call multiple logical the database from a single program and nested as required. A logical database can also is called more than once in a program, if programmed accordingly.

Note

When creating a logical database in logical database Builder, the following order should is kept, since this then makes it Easier to generate proposal for the remaining components from the those already created. Some of the most important properties of a logical database is defined at the same time as its structure. After the definition of the structure, a proposal are created for the selection include. The structure and selection include is used to generate a template for the database program. These components can then quickly is used to create a ready-to-run logical database, in which further requirements can is Implemented.

Create the structure based on a root node.
Associate it with a search help.
Generate and edit the selection include.
Generate and edit the database program.
Edit further elements.

Translation: Logical Database (1): composition