ABAP Keyword Documentation → ABAP - Dictionary → ABAP CDS in ABAP Dictionary → ABAP CDS - Data Definitions → ABAP CDS - DDL for Data Definitions → ABAP CDS - DEFINE VIEW → ABAP CDS - SELECT → ABAP CDS - SELECT, ASSOCIATION → ABAP CDS - path_expr
ABAP CDS - Joins of Associations
This example demonstrates how to implement path expressions in joins in ABAP CDS.
Other versions:
7.31 | 7.40 | 7.54
Source Code
DATA:
path_outer TYPE TABLE OF demo_cds_assoc_join1_o WITH DEFAULT KEY,
path_inner TYPE TABLE OF demo_cds_assoc_join1_i WITH DEFAULT KEY,
join_outer TYPE TABLE OF wa WITH DEFAULT KEY,
join_inner TYPE TABLE OF wa WITH DEFAULT KEY.
out->begin_section( 'CDS Views'
)->begin_section( 'Path with [left outer]' ).
SELECT *
FROM demo_cds_assoc_join1_o
INTO TABLE @path_outer.
SORT path_outer.
out->write( path_outer
)->next_section( 'Path with [inner]' ).
SELECT *
FROM demo_cds_assoc_join1_i
INTO TABLE @path_inner.
SORT path_inner.
out->write( path_inner
)->end_section( )->end_section(
)->begin_section( `Open SQL Joins`
)->begin_section(
`LEFT OUTER JOINs` ).
SELECT FROM
demo_cds_assoc_join1_o AS t1
LEFT OUTER JOIN
demo_cds_assoc_join2 AS t2 ON t2~d = t1~d_1
LEFT OUTER JOIN
demo_join3 AS t3 ON t3~l = t2~d
FIELDS t1~a_1,
t1~b_1,
t1~c_1,
t1~d_1,
t2~d AS d_2,
t2~e AS e_2,
t2~f AS f_2,
t2~g AS g_2,
t2~h AS h_2,
t3~i AS i_3,
t3~j AS j_3,
t3~k AS k_3,
t3~l AS l_3
INTO CORRESPONDING FIELDS OF TABLE @join_outer.
SORT join_outer.
out->write( join_outer
)->next_section( `INNER JOINs` ).
SELECT FROM
demo_cds_assoc_join1_i AS t1
INNER JOIN
demo_cds_assoc_join2 AS t2 ON t2~d = t1~d_1
INNER JOIN
demo_join3 AS t3 ON t3~l = t2~d
FIELDS t1~a_1,
t1~b_1,
t1~c_1,
t1~d_1,
t2~d AS d_2,
t2~e AS e_2,
t2~f AS f_2,
t2~g AS g_2,
t2~h AS h_2,
t3~i AS i_3,
t3~j AS j_3,
t3~k AS k_3,
t3~l AS l_3
INTO CORRESPONDING FIELDS OF TABLE @join_inner.
SORT join_inner.
out->write( join_inner )->display( ).
ASSERT path_inner = join_inner.
ASSERT path_outer = join_outer.
Description
This example demonstrates how joins are used for path expressions with CDS associations. The following two CDS views - DEMO_CDS_ASSOC_JOIN1_O and DEMO_CDS_ASSOC_JOIN1_I - access their own association _demo_join2 in path expressions of the SELECT list and the published CDS association _demo_join3 of DEMO_CDS_ASSOC_JOIN2.
@AccessControl.authorizationCheck: #NOT_REQUIRED
define view Demo_Cds_Assoc_Join1_o
as select from demo_join1
association to Demo_Cds_Assoc_Join2 as _demo_join2 on
_demo_join2.d = demo_join1.d
{
demo_join1.a as a_1,
demo_join1.b as b_1,
demo_join1.c as c_1,
demo_join1.d as d_1,
_demo_join2[left outer].d as d_2,
_demo_join2[left outer].e as e_2,
_demo_join2[left outer].f as f_2,
_demo_join2[left outer].g as g_2,
_demo_join2[left outer].h as h_2,
_demo_join2[left outer]._demo_join3[left outer].i as i_3,
_demo_join2[left outer]._demo_join3[left outer].j as j_3,
_demo_join2[left outer]._demo_join3[left outer].k as k_3,
_demo_join2[left outer]._demo_join3[left outer].l as l_3
}
@AccessControl.authorizationCheck: #NOT_REQUIRED
define view Demo_Cds_Assoc_Join1_i
as select from demo_join1
association to Demo_Cds_Assoc_Join2 as _demo_join2 on
_demo_join2.d = demo_join1.d
{
demo_join1.a as a_1,
demo_join1.b as b_1,
demo_join1.c as c_1,
demo_join1.d as d_1,
_demo_join2[inner].d as d_2,
_demo_join2[inner].e as e_2,
_demo_join2[inner].f as f_2,
_demo_join2[inner].g as g_2,
_demo_join2[inner].h as h_2,
_demo_join2[inner]._demo_join3[inner].i as i_3,
_demo_join2[inner]._demo_join3[inner].j as j_3,
_demo_join2[inner]._demo_join3[inner].k as k_3,
_demo_join2[inner]._demo_join3[inner].l as l_3
}
@AccessControl.authorizationCheck: #NOT_REQUIRED
define view Demo_Cds_Assoc_Join2
as select from demo_join2
association [*] to demo_join3 as _demo_join3 on
_demo_join3.l = demo_join2.d
{
_demo_join3,
demo_join2.d,
demo_join2.e,
demo_join2.f,
demo_join2.g,
demo_join2.h
}
LEFT OUTER and INNER are explicitly specified in the path expressions.
- LEFT OUTER affects the implementation of CDS associations in a left outer join, which is the default behavior at these places.
- INNER affects the implementation of CDS associations in an inner join, which overwrites the default behavior at these places.
In the DDL Source Text Editor of the ADT, you can view the relevant configuration of the join in the display of the generated SQL DDL statement.
This example shows that the result sets of the CDS views DEMO_CDS_ASSOC_JOIN1_O and DEMO_CDS_ASSOC_JOIN1_I
are identical to the result sets of ABAP SQL statements
SELECT with explicitly programmed left outer and inner joins. The CDS views and the database
table DEMO_JOIN3 above are accessed. All involved database tables are filled with sample data. With
an inner join, unlike a left outer join, only the row is returned for which the join condition t3~l = t2~d is fulfilled.