Abap course chapter 4 database accesses

ABAP Course

Chapter 4 – Database accesses

Lecturer: André Bögelsack, UCC Technische Universität München
Author: Valentin Nicolescu, André Bögelsack
ABAP Course André Bögelsack, Valentin Nicolescu 1

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Agenda

1. Data dictionary
2. SAP flight example
3. Database operations in SAP
4. SAP OpenSQL
5. Types of database changes
6. 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
Domain ZY_ID INT4 Data type

Data element ZY_ID ZZ_ID

Field ZY_ID ZZ_ID

Structure Field

Table Field
Field


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
Connection Flight Reservation Plane

SPFLI SFLIGHT SBOOK SAPLANE
MANDT MANDT MANDT MANDT
CARRID CARRID CARRID PLANETYPE
CONNID CONNID CONNID SEATSMAX
AIRPFROM FLDATE FLDATE TANKCAP
AIRPTO SEATSMAX BOOKID CAP_UNIT
CITYFROM SEATSOCC CUSTOMID WEIGHT
CITYTO PRICE LUGGWEIGH WIE_UNIT
COUNTRYFR CURRENCY WUNIT OP_SPEED
COUNTRYTO PLANETYPE CANCELLED SPEED_UNIT
… … … …


SAP OpenSQL
• Independent from database

Application Server Database Server

ABAP-Interpreter DB-Interface SQL-Database

Select * from OpenSQL Native SQL
DB data DB data

Exec SQL. Native SQL
Select * from Data
End Exec. 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 runtime
2. 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 access
Internal tables and workareas:
wa_spfli
Workarea • Use the workarea to modify
LH 0400 (one row) one data set

it_spfli
Internal table • Use the internal table to store
AA 0017 (selected content) the selected database content
temporarily
LH 0400 • Internal tables are deleted
after program is finished

Database Database table • Use the database to read/write
(whole content) 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


Abap course chapter 4 database accesses

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