Logical data base

Former Member — Tue, 11 Mar 2008 11:14:21 GMT

i need some information about logical database VVAV, can anyone explain baout it ???

Re: Logical data base

Former Member — Tue, 11 Mar 2008 11:31:29 GMT

Use logical databases to read logically consistent data from databases. Each logical database has a

structure containing a hierarchy of those tables and views that are to be read.

You can attach exactly one logical database to each type 1 program. The logical database then supplies

your program with entries from tables and views. This means that you only need to program the data

processing statements.

Are special data collection programs data delivered by SAP

Provide your program with data in a hierarchically logical

sequence

Contain data base accesses that have been optimized for

performance

Supply a dynamic selection screen

Contain all necessary authorization checks

You can attach a logical database to each type 1 program

using the program attributes.

Special event blocks are also available for processing

individual records.

Every logical database is an encapsulated data collection program for frequent database access.

The database access has been optimized using Open SQL.

If you are working with a logical database, you do not need to program a selection screen for user entry,

since this is created automatically.

The system performs authorization checks according to the SAP authorization concept.

The NODES <node> statement performs two functions:

It defines a data object (a structure) as a table work area that has the same structure as the ABAP

Dictionary Structure <node>, that is a node of the hierarchical structure of the logical database. This

structure is then filled at runtime with data records that the logical database has read from the

database and made available to the program.

It determines how detailed the selection screen is: The selection screen that has been defined in

the logical database should contain only those key information input fields that the program needs.

The NODES statement allows you to ensure only information from relevant tables is available to the

selection screen.

Logical databases read according to their structure from top to bottom. The depth of data read depends

on a program's GET statements. The level is determined by the deepest GET statement (from the logical

database's structural view).

Logical databases are included in type 1 programs as program attributes. Only one logical database can

be attached per program.

You can tell a logical database exactly which fields you need from the database using the GET addition

FIELDS. If the logical database supports this action, then it will read only those fields specified from the

database.

If you need database table data for a list that is not supplied by your logical database, you can program

any additional database access needed using SELECT.

You can include a logical database in every type 1 program using the program attributes.

Each node in the logical database's hierarchy also provides you with a GET event block (in addition to

the other event blocks). (GET SPFLI, GET SFLIGHT, GET SBOOK in the example above).

You can program individual record processing within these GET event blocks.

At runtime the event blocks that create lists are processed, in the following order:

START-OF SELECTION.

GET SPFLI and GET SFLIGHT are called several times in nested SELECT logic according to the

structure of the logical database.

END-OF-SELECTION is called after all GET events, and immediately before the list is sent to the

presentation server.

At runtime the event blocks that create lists are processed in the following order:

START-OF-SELECTION.

GET spfli: the first data record from database table SPFLI that corresponds to the selection criteria

is placed in work area spfli and the event block is processed.

GET sflight: the first data record from SFLIGHT that corresponds to the selection criteria as well as

to the key of the current SPFLI record is placed in work area sflight and the event block is

processed.

GET sflight: the next data record from database table SFLIGHT is placed in work area sflight and

the event block is processed again.

GET sflight: is called again until no further corresponding data records are found.

GET spfli LATE is called before the next data record from SPFLI is placed in work area spfli.

GET spfli: The logical database places the next corresponding data record from SPFLI in work

area spfli.

...

END-OF-SELECTION: is called immediately before the list is sent.

Do Reward if helpful

Re: Logical data base

Former Member — Tue, 11 Mar 2008 11:39:26 GMT

hi ,

goto se36 --> enter the name of the ldb and goto the documentation for this may it helps u.

Report RVDBVAV0 is a sample program for this ldb.

regards,

venkat.

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