ABAP/4 ОКМ ДМ экономическая информатика 4GL Теория и практика обработки информации

Компьютерный язык ABAP/4 - ключевые слова

ORDER BY clause

Variants

1. ... ORDER BY PRIMARY KEY
2. ... ORDER BY f1 ... fn
3. ... ORDER BY (itab)

Effect

Orders the records in a SELECT command. Without the ORDER-BY clause, the order in which the selected lines are supplied is undefined. This means that two similar SELECT commands may produce lines in a different order.

Variant 1

...ORDER BY PRIMARY KEY

Effect

Sorts the selected lines in ascending order by the primary key of the database table. This variant is only permitted for SELECT * ... .

Example

Output the passenger list for the Lufthansa flight 0400 on 28.02.1995:


TABLES SBOOK.

SELECT * FROM SBOOK
         WHERE
           CARRID  = 'LH '      AND
           CONNID  = '0400'     AND
           FLDATE  = '19950228'
         ORDER BY PRIMARY KEY.
  WRITE: / SBOOK-BOOKID, SBOOK-CUSTOMID,   SBOOK-CUSTTYPE,
           SBOOK-SMOKER, SBOOK-LUGGWEIGHT, SBOOK-WUNIT,
           SBOOK-INVOICE.
ENDSELECT.

Notes

Since views do not have a primary key, specifying ORDER BY PRIMARY KEY only makes sense with database tables. If, however, you do specify ORDER BY PRIMARY KEY with a view, all fields of the view are sorted in ascending order.

Variant 2

ORDER BY f1 ... fn

Effect

Sorts the selected records in ascending order by the specified database fields f1 ... fn . If a list is also specified in the SELECT clause , the fields f1, ..., fn must appear in this list.

By supplementing the statement with DESCENDING , you can sort in descending order using any of the fields f1, ..., fn .

The default sort sequence is ascending order, but you can make this explicit by adding the addition ASCENDING .

Examples

Output Lufthansa flights from 27.02.1995 to 05.03.1995, sorted by plane type and number of occupied seats:


TABLES: SFLIGHT.

SELECT * FROM SFLIGHT
         WHERE CARRID = 'LH' AND
               FLDATE BETWEEN '19950227' AND '19950305'
         ORDER BY PLANETYPE ASCENDING SEATSOCC DESCENDING.
  WRITE: / SFLIGHT-PLANETYPE, SFLIGHT-SEATSOCC, SFLIGHT-CONNID,
           SFLIGHT-FLDATE.
ENDSELECT.

Notes

Pooled and cluster tables can only be sorted by their primary key.
With a SELECT * ... , the client field automatically becomes the first sort criterion in client-specific tables, unless the addition CLIENT SPECIFIED is specified in the FROM clause .
Specifying FOR ALL ENTRIES IN itab WHERE ... in the WHERE clause excludes ORDER BY f1 ... fn .

Notes

Performance

Notes

In contrast to ... ORDER BY PRIMARY KEY , ORDER BY f1 ... fn is not automatically supported by a (sorted) index . Without an index, you must sort the result set at runtime. Because of the SAP architecture, this should not be performed on the database server, but on the applications server. If it does not make sense to create an index, you should not sort the result set with ... ORDER BY f1 ... fn on the database server, but with SORT on the applications server.
With larger datasets, you should only use the variant ORDER BY f1 ... fn if the order of the database fields f1 ... fn is exactly the same as the order of the indexes.

Variant 3

... ORDER BY (itab)

Effect

Works like ORDER BY f1 ... fn if the internal table itab contains the list f1 ... fn as ABAP/4 source code. The internal table itab must only have one field. This must be a type C field and must not be more than 72 characters long. itab must be specified in parentheses. There must be no blanks between the parentheses and the table name.

Note

The same restrictions apply to this variant as to ORDER BY f1 ... fn .

Example

Output all Lufthansa points of departure with the number of destinations:


TABLES: SPFLI
DATA:   BEGIN OF WA.
          INCLUDE STRUCTURE SPFLI.
DATA:     COUNT TYPE I:
DATA:   END OF WA.
DATA:   GTAB(72) OCCURS 5 WITH HEADER LINE,
        FTAB(72) OCCURS 5 WITH HEADER LINE,
        OTAB(72) OCCURS 5 WITH HEADER LINE,
        COUNT TYPE I.

REFRESH: GTAB, FTAB, OTAB.
FTAB = 'CITYFROM COUNT( * ) AS COUNT'. APPEND FTAB.
GTAB = 'CITYFROM'.                     APPEND GTAB.
OTAB = 'CITYFROM'.                     APPEND OTAB.

SELECT DISTINCT (FTAB)
       INTO CORRESPONDING FIELDS OF WA
       FROM SPFLI
       WHERE
         CARRID   = 'LH'
       GROUP BY (GTAB)
       ORDER BY (OTAB).


  WRITE: / WA-CITYFROM, WA-COUNT.
ENDSELECT.

ABAP/4 ОКМ ДМ экономическая информатика 4GL Теория и практика обработки информации

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