Abap course chapter 4 database accesses

ABAP Course André Bögelsack, Valentin Nicolescu 1

ABAP Course

Chapter 4 – Database accesses

Lecturer: André Bögelsack, UCC Technische Universität MünchenAuthor: Valentin Nicolescu, André Bögelsack


Copyright 2008 UCC TU München All rights reserved

Weitergabe und Vervielfältigung dieser Publikation oder von Teilen daraus sind, zu welchem Zweck und in welcher Form auch immer, ohne die ausdrückliche schriftliche Genehmigung durch HCC TU München nicht gestattet. In dieser Publikation enthaltene Informationen können ohne vorherige Ankündigung geändert werden.

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Agenda

1. Data dictionary2. SAP flight example3. Database operations in SAP4. SAP OpenSQL5. Types of database changes6. Types of entry help


Data dictionary

• Data dictionary = global directory for data types• Assignment of help texts and explanations for data types in

different languages• ERM can be shown as a figure automatically• Most important objects: structure, table, data element and

domain


Data dictionary

ZY_ID

ZY_ID

INT4

ZZ_ID

Domain

Data element

Data type

Field ZY_ID ZZ_ID

Structure Field

Field

Field

Table


Data dictionary

• Menu path: Tools • ABAP Workbench • Development • Dictionary

• TA SE11• View, edit, delete, create tables, data types, domains definitions

etc.• Tables and views from the ABAP dictionary represent tables and

views from the database• User interface are generated automatically when changing views,

tables etc.• Table may be changed after they are created without losing data• SAP tables may be extended by APPEND structures


Data browser

• Menu path: Tools • ABAP Workbench • Overview • Data Browser

• TA SE16• View table content• Add new entries to tables when adding is permitted for the table• Browse the entry help table content• Copy table content to transport request• Download table content


Overview about all objects• Database table• View• Data type

– Data element– Structure– Database table– Table types– Views– Class / interface

• Type group• Domain• Search help• Lock object


Visualization

• Foreign key relationships can be visualized in data dictionary• Table SFLIGHT


SAP flight example

• Created and maintained by SAP to demonstrate database operations

• Contains exercise data for airline, flight connection number, flight date, airfare etc.

• Report for data generation: S_FLIGHT_MODEL_DATA_GENERATION

• SAP trainings, examples from books build refer to the flight example


SAP flight example – table structure

MANDT

SPFLI

Connection Flight Reservation Plane

SFLIGHT SBOOK SAPLANE

CARRID

CONNID

AIRPFROM

AIRPTO

CITYFROM

CITYTO

COUNTRYFR

COUNTRYTO

…

MANDT

CARRID

CONNID

FLDATE

SEATSMAX

SEATSOCC

PRICE

CURRENCY

PLANETYPE

…

MANDT

CARRID

CONNID

FLDATE

BOOKID

CUSTOMID

LUGGWEIGH

WUNIT

CANCELLED

…

MANDT

PLANETYPE

SEATSMAX

TANKCAP

CAP_UNIT

WEIGHT

WIE_UNIT

OP_SPEED

SPEED_UNIT

…


SAP OpenSQL• Independent from database

Application Server

ABAP-Interpreter DB-Interface

Database Server

SQL-Database

Data

Select * from

Exec SQL. Select * fromEnd Exec.

OpenSQL Native SQL

DB data DB data

Native SQL

DB data


OpenSQL instructions

• Select:– SELECT / SELECT SINGLE– * / field 1 ..field n / – FROM table / view– INTO structure / internal table– WHERE condition

• Aggregation:– MAX, MIN, AVG– SUM, COUNT

• Joins:– Left outer join– Inner join– View


Procedure for database access

General:• Be specific to decrease the load on the database• Access to database takes 10,000 time longer than access to buffers• Avoid table scans, use indexes

Procedure:1. Read database data into internal tables

• Internal tables are tables for holding data during runtime2. Change data per row

• Use workareas to hold one row of the table and change data in the workarea

3. Write changes back to database


Procedure for database accessInternal tables and workareas:

Database

AA 0017LH 0400

LH 0400 Workarea(one row)

Internal table(selected content)

Database table(whole content)

wa_spfli

it_spfli

• Use the workarea to modify one data set

• Use the internal table to store the selected database content temporarily

• Internal tables are deleted after program is finished

• Use the database to read/write data


Types of database changes

Modify instruction:MODIFY <dbtable> [CLIENT SPECIFIED] FROM <workarea>.MODIFY <dbtable> [CLIENT SPECIFIED] FROM TABLE <internaltable>

• Modify = Update – the command updates the database table if the database table already contains dataset

• Modify = Insert – the command inserts new datasets into the database table

Delete instruction:DELETE FROM <dbtable> WHERE [SQL statement].


Entry help• Entry help uses a table in the background• Predefined entry help for a table