What does it do? This variant of the component operator CORRESPONDING can only be used for internal tables. The expression constructs an internal table from the components of the internal table itab and a lookup table lookup_tab. The lines of the internal table result from a comparison of itab and lookup_tab. The target type specified using dtype or # must be a table type. The parameters itab and lookup_tab expect internal tables whose line type must be structured. In addition, itab must be convertible to the target type. itab and lookup_tab are general expression positions. The result of the expression is created in the following steps:
First, an interim result of the type of the internal table itab is constructed as follows: For each line in itab, the lookup table lookup_tab searches for a line that has the same content in the columns s1, s2, ... as the columns t1, t2 , ... of the line in itab. The search must be performed using a sorted table key or a hash key (see below). If the key is not unique, the first line found is used.
If no line like this is found, a line with the unchanged content of the line in itab is inserted into the interim result.
If such a line is found, a line is inserted into the interim result that is the result of an assignment of the line found in itab to the current line in lookup_tab. By default, the assignment is made in accordance with the rules of MOVE-CORRESPONDING for structures with the addition EXPANDING NESTED TABLES, with the exception that the components used for searches are not assigned by default: The components s1, s2, ... of lookup_tab used for the search are by default not assigned to the identically named components of itab and the components t1, t2, ... of itab used for searches are not assigned the identically named components of lookup_tab.
The interim result of the type of the table itab is assigned to the result of the expression in accordance with the regular assignment rules for internal tables and, if necessary, converted to the target type. This means that the component by component assignment takes place between the lookup table lookup_tab as the source table and an interim result with the type of itab as the target table. A mapping rule mapping can be used to override the default assignment of identically named components and the default exclusion of the components s1, s2, ... and t1, t2, ... The same internal table can only be specified for itab and lookup_tab if this is known statically. If it is only known at runtime, the expression cannot be evaluated and the runtime error CORRESPONDING_SELF occurs. The search for the line in lookup_tab must take place using a sorted table key or a hash key:
If the addition KEY is not specified, a sorted table or a hashed table must be specified for lookup_tab.
If the addition KEY is specified, the key key_name specified after it is used. The following can be specified for key_name:
A secondary key using its name
The primary key using its predefined name primary_key or an alias. If the primary key is specified, lookup_tab must be a sorted table or a hashed table. The comparison fields s1, s2, ... must completely cover the used table key.
Latest notes:
Unlike the basic form, this variant does not have the addition DEEP. Instead, it always behaves as if DEEP were specified. The addition BASE cannot be specified either.
Generally, the type of itab and the target type should be identical.
In a common use case, an existing internal table itab is enriched with information from the lookup table lookup_tab. Here, the constructor expression is assigned to the same internal table as specified for itab. In this case, the expression is optimized internally to work directly with itab without creating an interim result.
If the constructor expression is not assigned to the internal table specified for itab or if this table is not known statically, the temporary interim result with the type itab must be created completely. This produces a syntax check warning that can be hidden by a pragma.
If the same table is specified for itab and lookup_tab , a temporary copy of the table must be created as a target table of the assignment. If this is detected by the syntax check, a warning occurs that can be hidden by a pragma. If this is not detected until runtime, the information needed to create the necessary temporary copy of the target object is missing and runtime error CORRESPONDING_SELF occurs.
The variant should not be used with the addition EXACT which produces a syntax warning. NON_V5_HINTS ABAP_HINT_END
ABAP_EXAMPLE_VX5 Lines of internal table itab1 that exist in internal table itab2 are passed to itab1. ABEXA 00973 ABAP_EXAMPLE_END
