Chapter 4 – Database accesses ABAP Course Chapter 4 – Database accesses Lecturer: André Bögelsack, UCC Technische Universität München Author: Valentin Nicolescu, André Bögelsack

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Agenda Data dictionary SAP flight example Database operations in SAP SAP OpenSQL Types of database changes 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 Field Field Field Domain ZY_ID INT4 Data type Data element ZY_ID ZZ_ID Field ZY_ID ZZ_ID Field Structure 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 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 Data Exec SQL. Select * from End Exec. Native SQL DB data

OpenSQL instructions Select: Aggregation: Joins: 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: Read database data into internal tables Internal tables are tables for holding data during runtime Change data per row Use workareas to hold one row of the table and change data in the workarea Write changes back to database

Procedure for database access Internal tables and workareas: wa_spfli LH 0400 Workarea (one row) Use the workarea to modify one data set it_spfli Use the internal table to store the selected database content temporarily Internal tables are deleted after program is finished AA 0017 LH 0400 Internal table (selected content) Database Database table (whole content) 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