chapter 13_database operations

8/12/2019 Chapter 13_Database Operations

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2005 IBM CorporationDatabase Operations | 6.13 March-2005

Database Operations


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2005 IBM Corporation2 March-2005Database Operations | 6.13

Objectives

The participants will be able to:

Manipulate data in the database tables using:

UPDATE

INSERT

MODIFY

DELETE

Understand a logical unit of work (LUW)

Know how and when to use a COMMIT vs. A ROLLBACK


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Overview

Academy Awards

Year

Category

1994

PIC

Winner Forrest Gump

Notes Tom Hanks had an Oscar-winning performance.

Critic Dean

UPDATE

INSERTMODIFY

DELETE

We will now add functionality to the Updatepushbutton by learning the database operation

UPDATE. We will also learn INSERT, MODIFY,

and DELETE.

UpdateExit

Enter Name

YMOVIEDatabase Table


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Open versus Native SQL

ABAP

Program

Open SQL

Native SQL

Database

Interface

Layer

** MZA08TOP - Top Include **

PROGRAM SAPMZA08 MESSAGE-ID ZA.

TABLES YMOVIE.

DATA OKCODE(4).

UPDATEINSERT

MODIFY

DELETE


TABLES statement

defines the work area forYMOVIE table


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Open versus Native SQL (Contd.)

ABAP

Program

Open SQL

Native SQL

Database

Interface

Layer

** MZA08TOP - Top Include **

PROGRAM SAPMZA08 MESSAGE-ID ZA.

TABLES YMOVIE.

DATA OKCODE(4).

UPDATEINSERT

MODIFY

DELETE


TABLES statement

defines the work area forYMOVIE table


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Update

UPDATE YMOVIE.Use values in field string created with

TABLES statement to update allfields

of onerecord.

UPDATE YMOVIESET WINNER = Forrest Gump

NOTES = Great movie!

WHERE AAYEAR = 1994

AND CATEGORY = PIC.

Update the specified fields of onerecord (because full primary key is

used in the WHERE clause).

UPDATE YMOVIE

SET NOTES = Great movie!

WHERE CATEGORY = PIC.

Update the specified field of multiple

records (because full primary key is

notused in the WHERE clause).


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Insert

INSERT YMOVIE.Use values in field string

created with TABLES

statement to insert onerecord.

INSERT INTO YMOVIE

VALUES MOVIE_REC.Use values in MOVIE_REC field

string to insert onerecord.

MOVIE_REC field string must be at least

the same length as a record in YMOVIE.


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Modify

MODIFY YMOVIE.Use values in field string created with

TABLES statement to modify onerecord.

MODIFY YMOVIEFROM MOVIE_REC. Use values in MOVIE_REC field

string to modify onerecord.

If the record does notexist, MODIFY will insertthe record.

If the record does exist, MODIFY will updatethe record.

MOVIE_REC field string must be at leastthe same length as a record in YMOVIE.


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Delete

DELETE YMOVIE.Use values in field string created with

TABLES statement to delete onerecord.

DELETE FROM YMOVIE

WHERE AAYEAR = 1994

AND CATEGORY = PIC.

Use values in WHERE clause to delete

onerecord (because full primary key is

used in the WHERE clause).

DELETE FROM YMOVIE

WHERE CATEGORY = PIC.

Use values in WHERE clause to delete

multiplerecords (because full primary

key is notused in the WHERE clause).


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UPDATE YMOVIE FROM TABLE MOVIE_ITAB.

INSERT YMOVIE FROM TABLE MOVIE_ITAB.

MODIFY YMOVIE FROM TABLE MOVIE_ITAB.

DELETE YMOVIE FROM TABLE MOVIE_ITAB.

Internal Table Database Operations

MOVIE_ITAB internal table

must be at least the same length

as the pr imary keyof YMOVIE.

MOVIE_ITAB internal table

must be at least the same length

as a recordin YMOVIE.


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Logical Unit of Work

Screen

1

Database

Transaction

Screen

2

Database

Transaction

Screen

3

Database

Transaction

Update Transaction

(Logical Unit of Work)

SELECT ASELECT B

UPDATE A DELETE B


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Commit or Rollback

** MZA08I01 - PAI Modules **

MODULE UPDATE INPUT.

IF OKCODE = UPDA.

UPDATE YMOVIE.

IF SY-SUBRC = 0.

COMMIT WORK.

MESSAGE S002.

ELSE.

ROLLBACK WORK.MESSAGE I003.

ENDIF.

ENDIF.

ENDMODULE.

Update

If the update is successful, the

changes will be confirmed in

the database.

If the update isnot successful,

the changes will be cancelled

and rolled back from the database.


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Because SQL statements are not standardized across database systems,SAP has two forms of SQL statements: Open SQL and Native SQL.

The ABAP Open SQL statement UPDATE will change an already existing

record (or records) in the database table.

The ABAP Open SQL statement INSERT will add a non-existing record to

the database table. A way to avoid an error with UPDATE or INSERT is to use MODIFY. The

ABAP Open SQL statement MODIFY will either insert a record (if the record

does not exist) or update a record (if the record already exists).

The ABAP Open SQL statement DELETE will remove an already existing

record (or records) from the database table. If you are going to perform these database operations on several records, it is

more efficient to use an internal table. If you use an internal table, these

database operations are called array operations.

Summary


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Summary (Contd.)

The term logical unit of work (LUW) refers to a collection of all-or-nothingactions performed at the database level as a complete unit.

The ABAP statement COMMIT WORK confirms all changes to the database

and closes an LUW. The ABAP statement ROLLBACK WORK cancels and

rolls back all changes in an LUW.

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