collect vs append.

[Former Member]

what does a collect statement mean to a database table?

why one shouldnot do an aapend after a row has been added to a database table using COLLECT?

[Former Member]

Both statement used to populate data in internal table whan u use append statement then a new record has been appended to internal table and when u use collect statement then program will check key for character fields and for same character fields it will add all numeric fields.

ex:

APPEND line_spec TO itab SORTED BY comp result.

Addition:

... SORTED BY comp

Effect

This statement appends one or more rows line_spec to an internal index table itab. If itab is a standard table, you can use SORTED BY to sort the table in a specified way. Use result when appending a single row as of release 6.10 to set a reference to the appended row in the form of a field symbol or a data reference.

For the individual table types, appending is done as follows:

To standard tables, rows are appended directly and without checking the content of the internal table.

To sorted tables, rows are appended only if they correspond to the sort sequence and do not create duplicate entries with unique table key. Otherwise, an untreatable exception is triggered.

To hashed tables, no rows can be appended.

The APPEND statement sets sy-tabix to the table index of the last appended row.

Addition

... SORTED BY comp

Effect

This addition is allowed only if you specify a workarea wa and if you use a standard table, where wa must be compatible to the row type of the table. You can specify component comp as shown in section Specifying Components, however, you can access only one single component and no attributes of classes using the object component selector.

The statement is executed in two steps:

Starting at the last row, the table is searched for a row, in which the value of component comp is greater than or equal to the value of component comp of wa. If such a row exists, the workarea wa is included after this row. If no such row exists, the workarea wa is included before the first row. The table index of all rows following the included rows increases by one.

If the number of rows before the statement is executed is greater than or equal to the number specified in the definition of the internal table in the INITIAL SIZE addition, the newly-created last row is deleted.

Note

When using only the statement APPEND with addition SORTED BY to fill an internal table, this rule results in an internal table that contains no more than the number of rows specified in its definition after INITIAL SIZE and that is sorted in descending order by component comp (ranking).

The SORT statement should usually be used instead of APPEND SORTED BY.

Example

Creating a ranking of the three flights of a connection showing the most free seats.

PARAMETERS: p_carrid TYPE sflight-carrid,

p_connid TYPE sflight-connid.

DATA: BEGIN OF seats,

fldate TYPE sflight-fldate,

seatsocc TYPE sflight-seatsocc,

seatsmax TYPE sflight-seatsmax,

seatsfree TYPE sflight-seatsocc,

END OF seats.

DATA seats_tab LIKE STANDARD TABLE OF seats

INITIAL SIZE 3.

SELECT fldate seatsocc seatsmax

FROM sflight

INTO seats

WHERE carrid = p_carrid AND

connid = p_connid.

seats-seatsfree = seats-seatsmax - seats-seatsocc.

APPEND seats TO seats_tab SORTED BY seatsfree.

ENDSELECT.

COLLECT

Syntax

COLLECT wa INTO itab result.

Effect

This statement inserts the contents of a work area wa either as single row into an internal table itab or adds the values of its numeric components to the corresponding values of existing rows with the same key. As of Release 6.10, you can use result to set a reference to the inserted or changed row in the form of a field symbol or data reference.

Prerequisite for the use of this statement is that wa is compatible with the row type of itab and all components that are not part of the table key must have a numeric data type (i, p, f).

In standard tables that are only filled using COLLECT, the entry is determined by a temporarily created hash administration. The workload is independent of the number of entries in the table. The hash administration is temporary and is generally invalidated when the table is accessed for changing. If further COLLECT statements are entered after an invalidation, a linear search of all table rows is performed. The workload for this search increases in a linear fashion in relation to the number of entries.

In sorted tables, the entry is determined using a binary search. The workload has a logarithmic relationship to the number of entries in the table.

In hashed tables, the entry is determined using the hash administration of the table and is always independent of the number of table entries.

If no line is found with an identical key, a row is inserted as described below, and filled with the content of wa:

In standard tables the line is appended.

In sorted tables, the new line is inserted in the sort sequence of the internal table according to its key values, and the table index of subsequent rows is increased by 1.

In hashed tables, the new row is inserted into the internal table by the hash administration, according to its key values.

If the internal table already contains one or more rows with an identical key, those values of the components of work area wa that are not part of the key, are added to the corresponding components of the uppermost existing row (in the case of index tables, this is the row with the lowest table index).

The COLLECT statement sets sy-tabix to the table index of the inserted or existing row, in the case of standard tables and sorted tables, and to the value 0 in the case of hashed tables.

Outside of classes, you can omit wa INTO if the internal table has an identically-named header line itab. The statement then implicitly uses the header line as the work area.

COLLECT should only be used if you want to create an internal table that is genuinely unique or compressed. In this case, COLLECT can greatly benefit performance. If uniqueness or compression are not required, or the uniqueness is guaranteed for other reasons, the INSERT statement should be used instead.

The use of COLLECT for standard tables is obsolete. COLLECT should primarily be used for hashed tables, as these have a unique table key and a stable hash administration.

If a standard table is filled using COLLECT, it should not be edited using any other statement with the exception of MODIFY. If the latter is used with the addition TRANSPORTING, you must ensure that no key fields are changed. This is the only way to guarantee that the table entries are always unique and compressed, and that the COLLECT statement functions correctly and benefits performance. The function module ABL_TABLE_HASH_STATE can be used to check whether a standard table is suitable for editing using COLLECT.

Example

Compressed insertion of data from the database table sflight into the internal table seats_tab. The rows in which the key components carrid and connid are identical are compressed by adding the number of occupied seats to the numeric component seatsocc.

DATA: BEGIN OF seats,

carrid TYPE sflight-carrid,

connid TYPE sflight-connid,

seatsocc TYPE sflight-seatsocc,

END OF seats.

DATA seats_tab LIKE HASHED TABLE OF seats

WITH UNIQUE KEY carrid connid.

SELECT carrid connid seatsocc

FROM sflight

INTO seats.

COLLECT seats INTO seats_tab.

ENDSELECT.

reward points if helpfull

[Former Member]

hi,

COLLECT

Inserts lines into an internal table in summarized form.

Syntax

COLLECT <line> INTO <itab>.

The statement first checks whether the internal table contains an entry with the same key. If not, it acts like INSERT. If there is already a table entry with the same key, COLLECT does not insert a new line. Instead, it adds the values from the numeric fields of the work area <line> to the values in the corresponding fields of the existing table entry.

APPEND

Appends one or more lines to the end of an index table.

Syntax

APPEND <line>|LINES OF <jtab> TO <itab>.

Appends one line <line> or several lines of an internal table <jtab> to the index table <itab>.

Hope this helps u,

Regards,

Arunsri

[Former Member]

Hi,

APPEND allows the duplicates,it never check the records already exists or not.

COLLECT checks the records and insert the record if it doesn't exist,if it is exists then collect statement change the record data(adds numeric field values) and insert into internal table.

Reward points,if it is useful.

Thanks,

chandu.

[Former Member]

Hi,

COLLECT

Aggregates lines and then adds them to an internal table.

Syntax

COLLECT <line> INTO <itab>

[ASSIGNING <FS> | REFERENCE INTO <dref>].

The system checks whether there is already a table entry that matches the key. If there is no corresponding entry already in the table, the COLLECT statement has the same effect as INSERT. If an entry with the same key already exists, the COLLECT statement does not append a new line, but adds the contents of the numeric fields in the work area <line> to the contents of the fields in the existing entry. If you use ASSIGNING or INTO REFERENCE, field symbol <FS> refers to the inserted line or the relevant data reference is stored in <dref> after the statement

APPEND

Appends a line or multiple lines to the end of an index table.

Syntax

APPEND <line>|LINES OF <jtab> TO <itab>

[ASSIGNING <FS> | REFERENCE INTO <dref>].

A line <line> or multiple lines of an internal table <jtab> are appended to index table <itab>. If you use ASSIGNING or INTO REFERENCE, field symbol <FS> refers to the appended line or the relevant data reference is stored in <dref> after the statement

Regards,

Priya.

[Former Member]

Hi,

The following special statement allows you to summate entries in an internal table:

COLLECT wa INTO itab.

itab must have a flat line type, and all of the fields that are not part of the table key must have a numeric type (f, i, p). You specify the line wathat you want to add as a work area that is compatible with the line type of itab.

When the line is inserted, the system checks whether there is already a table entry that matches the key. If there is no corresponding entry already in the table, the COLLECT statement has the same effect as inserting the new line. If an entry with the same key already exists, the COLLECT statement does not append a new line, but adds the contents of the numeric fields in the work area to the contents of the numeric fields in the existing entry.

REPORT demo_int_tables_COLLECT .

DATA: BEGIN OF line,

col1(3) TYPE c,

col2(2) TYPE n,

col3 TYPE i,

END OF line.

DATA itab LIKE SORTED TABLE OF line

WITH NON-UNIQUE KEY col1 col2.

line-col1 = 'abc'. line-col2 = '12'. line-col3 = 3.

COLLECT line INTO itab.

WRITE / sy-tabix.

line-col1 = 'def'. line-col2 = '34'. line-col3 = 5.

COLLECT line INTO itab.

WRITE / sy-tabix.

line-col1 = 'abc'. line-col2 = '12'. line-col3 = 7.

COLLECT line INTO itab.

WRITE / sy-tabix.

LOOP AT itab INTO line.

WRITE: / line-col1, line-col2, line-col3.

ENDLOOP.

The list output is:

1

2

1

abc 12 10

def 34 5

The example fills a sorted table. The first two COLLECT statements work like normal insertion statements. In the third COLLECTstatement, the first line of itab is modified.

APPEND :

IT IS USED TO GET THE RECORD FROM THE INTERNAL TABLE HEADER TO THE BODY AREA

IT ALLOWS DUPLICATION

COLLECT:

IT IS USED TO A GET A RECORD FROM HEADER TO THE BODY AREA BUT IT WILL NOT ALLOW ANY DUPLICATION EXCEPT IF THERE IS ANY NUMERIC FIELS IT ADDS THAT FIELDS DATA BUT NOT AS A NEW RECORD

Cheers,

vasavi.

kindly reward if helpful.