Всем привет!Как можно в запросе реализовать такую вещь.
Есть две прозрачные таблицы FIRST и SECOND.

select ........(какие-то поля)
from FIRST as F join SECOND as S on F~P1 = S~P1
and F~P2 = S~P2 and F~P3 = S~P3
into table itab
where ....какие-то условия

Дело в том если F~P3- имеет соответствующее значение S~P3 то выборка строк идёт по равенству значений F~P3 = S~P3,
а если F~P3 не имеет соответствующее значение S~P3 то нужно чтобы выбирались строки в которых S~P1 = пусто
Заранее благодарен

FROM Clause

Variants:
1. ... FROM dbtab [AS alias]

2. ... FROM tabref1 [INNER] JOIN tabref2 ON cond

3. ... FROM tabref1 LEFT [OUTER] JOIN tabref2 ON cond

4. ... FROM (source_text) [AS alias]

Ошибся S~P3 = пусто и можно немного изменить

select ........(какие-то поля)
from FIRST as F join SECOND as S on F~P1 = S~P1
and F~P2 = S~P2
into table itab
where F~P3 = S~P3 and....какие-то условия

напиши



выдержка из хелпа:
SELECT - join


Syntax
... [(] {dbtab_left [AS tabalias_left]} | join
{[INNER] JOIN}|{LEFT [OUTER] JOIN}
{dbtab_right [AS tabalias_right] ON join_cond} [)] ... .



Effect
The join syntax represents a recursively nestable join expression. A join expression consists of a left-hand and a right- hand side, which are joined either by means of [INNER] JOIN or LEFT [OUTER] JOIN . Depending on the type of join, a join expression can be either an inner ( INNER) or an outer (LEFT OUTER) join. Every join expression can be enclosed in round brackets. If a join expression is used, the SELECT command circumvents SAP buffering.

On the left-hand side, either a single database table, a view dbtab_left, or a join expression join can be specified. On the right-hand side, a single database table or a view dbtab_right as well as join conditions join_cond can be specified after ON. In this way, a maximum of 24 join expressions that join 25 database tables or views with each other can be specified after FROM.

AS can be used to specify an alternative table name tabalias for each of the specified database table names or for every view. A database table or a view can occur multiple times within a join expression and, in this case, have various alternative names.

The syntax of the join conditions join_cond is the same as that of the sql_cond conditions after the addition WHERE, with the following differences:

At least one comparison must be specified after ON.

Individual comparisons may be joined using AND only.

All comparisons must contain a column in the database table or the view dbtab_right on the right-hand side as an operand.

The following language elements may not be used: BETWEEN, LIKE, IN.

No sub-queries may be used.

For outer joins, only equality comparisons (=, EQ) are possible.

If an outer join occurs after FROM, the join condition of every join expression must contain at least one comparison between columns on the left-hand and the right-hand side.

In outer joins, all comparisons that contain columns as operands in the database table or the view dbtab_right on the right-hand side must be specified in the corresponding join condition. In the WHERE condition of the same SELECT command, these columns are not allowed as operands.

Resulting set for inner join

The inner join joins the columns of every selected line on the left- hand side with the columns of all lines on the right-hand side that jointly fulfil the join_cond condition. A line in the resulting set is created for every such line on the right-hand side. The content of the column on the left-hand side may be duplicated in this case. If none of the lines on the right-hand side fulfils the join_cond condition, no line is created in the resulting set.

Resulting set for outer join

The outer join basically creates the same resulting set as the inner join, with the difference that at least one line is created in the resulting set for every selected line on the left-hand side, even if no line on the right-hand side fulfils the join_cond condition. The columns on the right-hand side that do not fulfil the join_cond condition are filled with null values.


Example
Join the columns carrid, carrname and connid of the database tables scarr and spfli using an outer join. The column connid is set to the null value for all flights that do not fly from p_cityfr. This null value is then converted to the appropriate initial value when it is transferred to the assigned data object. The LOOP returns all airlines that do not fly from p_cityfr.

PARAMETERS p_cityfr TYPE spfli-cityfrom.

DATA: BEGIN OF wa,
carrid TYPE scarr-carrid,
carrname TYPE scarr-carrname,
connid TYPE spfli-connid,
END OF wa,
itab LIKE SORTED TABLE OF wa
WITH NON-UNIQUE KEY carrid.

SELECT s~carrid s~carrname p~connid
INTO CORRESPONDING FIELDS OF TABLE itab
FROM scarr AS s
LEFT OUTER JOIN spfli AS p ON s~carrid = p~carrid
AND p~cityfrom = p_cityfr.

LOOP AT itab INTO wa.
IF wa-connid = '0000'.
WRITE: / wa-carrid, wa-carrname.
ENDIF.
ENDLOOP.