09_ABAP – Advanced Internal Tables

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ABAP Advanced Internal Tables


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Contents

Objectives

Testing and Modifying Internal Table Contents

Obtaining Information about an Internal Table

Copying Data from one Internal Table to Another

Inserting Rows into an Internal Table

Modifying Rows in an Internal Table

Deleting Internal Table Contents

Filling an Internal Table Using COLLECT

Filling an Internal Table from a Database Table

Summary

Exercise / Q&A


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Contents

Objectives


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Objectives

Recognize the table body operator

to test for the existence of data in an itab

to compare the contents of two itabs for equality

Determine the number of rows in an itab: DESCRIBE and SY-TFILL

Copy the contents from one itab to another:

using the table body operator

the APPEND LINES and INSERT LINES statements

Use the INSERT and MODIFY statements to change the itab contents

Delete rows from an itab using DELETE, DELETE ... WHERE, CLEAR, CLEAR it[],

REFRESH, and FREE

Fill an itab using COLLECT

Fill an internal table from a database table using the most efficient constructs


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Contents

Testing and Modifying Internal

Table Contents


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Testing and Modifying Internal Table Contents

The table body operator: it[] DESCRIBE TABLE APPEND LINES INSERT LINES

INSERT MODIFY FREE DELETE

CLEAR REFRESH COLLECT


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The table body operator

itab it: the header & the body

it[]:means "the body of the internal table it.

to perform table operations that do not require

the header line

if itab does not have a header line:

it~ it[]: represent the body


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Contents

Obtaining Information about an

Internal Table


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Obtaining Information

Information:

Whether the internal table contains data?

How many rows it contains?

Determining Whether an itab Is Empty

IF it[] IS INITIAL.

Determining the Number of Rows in an itab

use DESCRIBE TABLE statement


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DESCRIBE TABLE Statement

Syntax: DESCRIBE TABLE it [LINES i] [OCCURS j].

where:

itis the name of an internal table.

iandjare numeric variables.

Effected system variables:

SY-TFILL: Number of rows (~ LINES i)

SY-TLENG: Length of a row in bytes


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Obtaining Information - example

REPORT y_vu_1201.DATA: BEGIN OF it OCCURS 3,

f1 VALUE 'X',

END OF it,

n TYPE i,

m TYPE i.

IF it[] IS INITIAL.

WRITE: / 'it is empty'.

ENDIF.

APPEND: it, it.

IF NOT it[] IS INITIAL.

WRITE: / 'it is not empty'.

ENDIF.

WRITE: / 'number of rows from sy-tabix:', sy-tabix.

DESCRIBE TABLE it LINES n OCCURS m.

WRITE: / 'number of rows from sy-tfill:', sy-tfill,

/ 'length of a row from sy-tleng:', sy-tleng,

/ 'occurs value :', m.


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Contents

Copying Data from one Internal

Table to Another


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Copying Data

it2[] = it1[].

to duplicate the contents of one itab in another

it1 & it2: same structure

any existing contents in it2 are overwritten

the header lines remain unchanged

Copying a Portion of an itab

APPEND LINES Statement

append rows to the end

INSERT LINES Statement

insert rows at a place


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APPEND LINES Statement

Syntax:

APPEND LINES OF it1 [FROM nf] [TO nt] TO it2.

where:

it1 and it2 are itabs with or without header lines (same structure)

nfand ntare numeric variables, literals, or constants

nf: index of the first row to be copied

nt: index of the last row to be copied

After APPEND LINES, SY-TABIX number of rows in the table


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INSERT LINES Statement

Syntax:

INSERT LINES OF it1 [FROM nf] [TO nt] INTO it2 [INDEX nb].

where:

it1 and it2 are itabs with or without header lines (samestructure)

nf, ntand nb are numeric variables, literals, or constants

nf: index of the first row to be inserted

nt: index of the last row to be inserted

nb: insert before row number nb


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Copying Data - examples

it1

APPEND LINES OF it1 FROM 2 TO 5 TO it2. it2

it2

it2

it2

INSERT LINES OF it1 FROM 8 INTO it2 INDEX 2.

LOOP AT it2.

IF it2-f1 >= 'E'.

INSERT LINES OF it1 TO 1 INTO it2.

ENDIF.

ENDLOOP.

it2[] = it1[].


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Comparing the Contents of Two Internal Tables

IF it1[] = it2[].

it1, it2: same structure

TRUE:

the same number of rows

and the contents of each row are the same


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Contents

Inserting Rows into an Internal

Table


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INSERT statement

Syntax: INSERT [wa INTO] it[INDEX n]

where: wa: a work area (same structure as it)

n: a numeric literal, variable, or constant

NOTES: ifwa is not specified insert the header line it

insert before row n

INSERT statement can be used inside or outside of LOOPAT it

outside: INDEX addition must be specified

inside: INDEX is optional; if not specified insert current row


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INSERT statement - examples

it-f1 = -99.

INSERT it INDEX 3.

LOOP AT it WHERE f1 >= 4.

it-f1 = -88.

INSERT it.

ENDLOOP.


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Contents

Modifying Rows in an Internal

Table


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MODIFY statement

Syntax:

MODIFY it[FROM wa] [INDEX n] [WHERE exp]]

where:

itis the name of an itab with or without a header line.

wa is a work area with the same structure as a row in thebody ofit.

n is a numeric literal, variable, or constant.

exp is a logical expression involving components ofit.

WHERE exp: cannot be used inside LOOP AT or with INDEX


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MODIFY statement - examples

it-f1 = 5.

it-f2 = 'Z'.

MODIFY it INDEX 4.

LOOP AT it.

it-f1 = it-f1 * 2.

MODIFY it.

ENDLOOP.


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Contents

Deleting Internal Table

Contents


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Deleting Internal Table Contents

FREE statement delete all rows free the associated memory

REFRESH statement delete all rows leave the memory allocated

CLEAR statement CLEAR it[]

delete all rows leave the memory allocated

CLEAR it clear the header line

DELETE statement delete one or more rows


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FREE and REFRESH

FREE statement Syntax: FREE it. NOTES:

All rows are deleted and all memory used by the body of the itab isfreed.

The header line, if it exists, remains unchanged.

REFRESH statement Syntax: REFRESH it. NOTES:

All rows are deleted, all memory used by the body of the itab remainsallocated.

The header line, if it exists, remains unchanged. FREE REFRESH:

Use FREE when finished using an itab before program ends Use REFRESH when delete all rows but intend to fill again


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FREE and REFRESH examplesREPORT y_vu_1207.

DATA: BEGIN OF it OCCURS 3,f1 LIKE sy-index,

END OF it,

i LIKE sy-index.

DO 3 TIMES.

i = sy-index.DO 3 TIMES.

it-f1 = i * sy-index.

APPEND it.

ENDDO.

WRITE: / ''.

LOOP AT it.

WRITE it-f1.ENDLOOP.

REFRESH it.

ENDDO.

FREE it.


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CLEAR Statement

Syntax: CLEARit| CLEARit[]

CLEARit[] same as REFRESH it


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DELETE Statement

Syntax

DELETE it (a) [INDEX n]

(b) [FROM i] [TOj]

(c) [WHERE exp] where:

n, i, andjare numeric literals, variables, or constants.

exp is a logical expression involving components of it.

NOTES:

DELETE itwithout any additions can only be usedinside LOOP AT it. deletes the current row.


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DELETE Statement - examples

DELETE it INDEX 5.

DELETE it FROM 6 TO 8.

DELETE it WHERE f1 BETWEEN 'B' AND 'D'.

LOOP AT it WHERE f1 BETWEEN 'E' AND 'J'.

DELETE it.

ENDLOOP.

READ TABLE it WITH KEY f1 = 'K' BINARY SEARCH.

IF sy-subrc = 0.

DELETE it INDEX sy-tabix.

ENDIF.


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Contents

Filling an Internal Table Using

COLLECT


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COLLECT Statement

collect totals within an itab while filling it

Syntax:

COLLECT [wa INTO] it.

where:

itis an internal table.

wa is a work area that has the same structure as it.

NOTES: add up the numeric fields (types I, P, and F) with the

same default key fields (type C, N, D, T, and X)


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COLLECT Statement - example

DATA: BEGIN OF it OCCURS 10,

date like sy-datum, " part of default keytot_sales TYPE p DECIMALS 2, "not part of default key

name(10), " part of default key

num_sales TYPE i VALUE 1, "not part of default key

END OF it.it-date = '20050901'.

it-tot_sales = 100.

it-name = 'Jack'.

COLLECT it.

it-date = '20050901'.

it-tot_sales = 200.

it-name = 'Jim'.

COLLECT it.

it-date = '20050901'.

it-tot_sales = 300.

it-name = 'Jack'.

COLLECT it.

it-date = '20050901'.

it-tot_sales = 400.

it-name = 'Jack'.

COLLECT it.

it-date = '20050901'.

it-tot_sales = 500.

it-name = 'Jim'.

COLLECT it.

it-date = '20050901'.

it-tot_sales = 600.

it-name = 'Jane'.

COLLECT it.

it-date = '20050902'.

it-tot_sales = 700.

it-name = 'Jack'.

COLLECT it.


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Contents

Filling an Internal Table from a

Database Table


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Filling an Internal Table from a Database Table

Selecting multiple rows directly into the body

of an internal table

multiple rows at 1 time

Selecting single rows into a work area and

then appending

Adding Rows one by one Using SELECT


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Selecting Multiple Rows Directly

use the INTO TABLE addition of the SELECT statement selected rows are placed in a single operation (array operation)

array operation: statement performs an operation on multiple rows of an itab

more efficient than single row operations

no work areas are used or needed

Syntax: (a) SELECT *

(b) SELECTf1 f2 . . .

FROM dbtab INTO [CORRESPONDING FIELDS OF] TABLE it.

where: dbtab is the name of a database table.

f1 andf2 are fields within dbtab.

itis the name of an itab.

NOTES: ENDSELECT is not used with INTO TABLE


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Example

REPORT y_vu_1301.

TABLES lfa1.

DATA it LIKE lfa1 OCCURS 23 WITH HEADER LINE.

SELECT * FROM lfa1 INTO TABLE it.

LOOP AT it.

WRITE: / it-lifnr, it-name1.

ENDLOOP.


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Some issues

SELECT INTO TABLE and Sorting

SELECT INTO TABLE, then SORT itab faster

SELECT ORDER BY

Selected Fields Must Fit into the Internal Table A row is retrieved from dbtab.

A row is allocated in it.

The fields from dbtab is moved byte-by-byte into the fields in it.

The data types and lengths of each sending field in dbtabshould match the receiving field in it. Any remaining fields in itare filled with initial values (blanks or zeros).


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Examples

REPORT y_vu_1302.

TABLES lfa1.

DATA BEGIN OF it OCCURS 2.

INCLUDE STRUCTURE lfa1.

DATA END OF it.

SELECT * FROM lfa1 INTO TABLE it

WHERE lifnr < '0000000010'.LOOP AT it.

WRITE: / it-mandt, it-lifnr, it-land1, it-name1.

ENDLOOP.

SKIP.

SELECT lifnr land1 name1 FROM lfa1 INTO TABLE it

WHERE lifnr < '0000000010'.

LOOP AT it.

WRITE: / it-mandt, it-lifnr, it-land1, it-name1.

ENDLOOP.


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Using the CORRESPONDING FIELDS Addition

moves fields with the same name

the same effect as the MOVE-CORRESPONDING

NOTES: The order of the sending and receiving fields does not

matter

Sending fields that do not have a corresponding

receiving field are discarded Receiving fields that do not have a corresponding

sending field are unchanged


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ExampleREPORT y_vu_1304.

TABLES lfa1.

DATA: BEGIN OF it1 OCCURS 23,

lifnr LIKE lfa1-lifnr,

lifnr_ext LIKE lfa1-lifnr,

land1 LIKE lfa1-land1,

END OF it1.

SELECT lifnr land1 FROM lfa1

INTO CORRESPONDING FIELDS OF TABLE it1

WHERE lifnr BETWEEN 'V10' AND 'V12'.


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Adding Rows one by one Using SELECT

Requires: the use of a work area omitting the TABLE addition

a second statement such as APPEND, INSERT, or COLLECT

TABLES lfa1.

DATA it LIKE lfa1 OCCURS 2 WITH HEADER LINE.

SELECT * FROM lfa1 INTO it "notice 'table' is omitted so the

WHERE land1 = 'DE'. "row goes into the header line of it

APPEND it.

ENDSELECT.

SELECT * FROM lfa1 "no 'into' so the row goes into theWHERE land1 = 'DE'. "default table work area

APPEND lfa1 TO it. "and then is appended to it

ENDSELECT.

Summing Up: Various Forms of


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Summing Up: Various Forms ofSELECT

Statement(s) Writes To

SELECT INTO TABLE it Body

SELECT INTO CORRESPONDINGFIELDS OF TABLE it

Body

SELECT INTO it Header line

SELECT INTO CORRESPONDINGFIELDS OF it

Header line


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Contents

Summary


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Summary

The table body operator IF it[] IS INITIAL: test for existence of data IF it1[] = it2[]: to compare two itabs for equality it2[] = it1[]: to duplicate an itab

DESCRIBE TABLE it[LINES i] [OCCURSj]. get attributes of an itab

APPEND LINES OF or INSERT LINES OF. To copy a portion of an itab from one to another

INSERT

inserts a row at any position MODIFY

modifies the contents of one or more rows


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Summary

DELETE removes one or more rows

CLEAR CLEAR it: clears the header line ofit CLEAR it[]: deletes all rows from itand leaves the memory

allocated REFRESH

deletes all rows and leaves the memory allocated (~ CLEARit[])

FREE deletes all rows and frees the memory

COLLECT to accumulate counts and totals

Documents

09_ABAP – Advanced Internal Tables