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Update FILTER operator

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Daniel Reger
2023-01-11 13:56:38 +01:00
parent b513b97294
commit 93a2788207
4 changed files with 285 additions and 80 deletions
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05_Constructor_Expressions.md
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@@ -704,30 +704,68 @@ DATA(b) = SWITCH #( a
## `FILTER`
- The
[`FILTER`](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenconstructor_expression_filter.htm)
operator constructs an internal table line by line based on an
existing table and conditions specified in a `WHERE` clause.
`FILTER` operator constructs an internal table according to a specified type (which can be an explicitly specified, non-generic table type or the # character as a symbol for the [operand type](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenoperand_type_glosry.htm) before the first parenthesis).
- The lines for the new internal table are taken from an
existing internal table based on conditions specified in a `WHERE` clause. Note that the table type of the existing internal table must be convertible to the specified target type.
- The conditions can either be based on single values or a [filter
table](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenconstructor_expr_filter_table.htm).
- Additions:
|Addition |Details |
|---|---|
|`USING KEY` | Specifies the [table key](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abentable_key_glosry.htm "Glossary Entry") with which the `WHERE` condition is evaluated, i. e. a [sorted key](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abensorted_key_glosry.htm "Glossary Entry") or a [hash key](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenhash_key_glosry.htm "Glossary Entry"). If the internal table has neither of them, a [secondary table key](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abensecondary_table_key_glosry.htm "Glossary Entry") must be available and specified. |
|`USING KEY` | Specifies the [table key](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abentable_key_glosry.htm "Glossary Entry") with which the `WHERE` condition is evaluated: either a [sorted key](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abensorted_key_glosry.htm "Glossary Entry") or a [hash key](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenhash_key_glosry.htm "Glossary Entry"). If the internal table has neither of them, a [secondary table key](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abensecondary_table_key_glosry.htm "Glossary Entry") must be available for the internal table which must then be specified after `USING KEY`. |
| `EXCEPT` | The specification of `EXCEPT` means that those lines of the existing table are used that do not meet the condition specified in the `WHERE` clause. Hence, if `EXCEPT` is not specified, the lines of the existing table are used that meet the condition. |
Examples:
``` abap
DATA(f1) = FILTER #( tab WHERE comp > 5 ).
```abap
"FILTER an conditions based on single values
"Assumption the component num is of type i.
DATA itab1 TYPE SORTED TABLE OF struc WITH NON-UNIQUE KEY num.
DATA itab2 TYPE STANDARD TABLE OF struc WITH NON-UNIQUE SORTED KEY sec_key COMPONENTS num.
DATA itab3 TYPE HASHED TABLE OF struc WITH UNIQUE KEY num.
DATA(f2) = FILTER #( tab EXCEPT WHERE comp < 3 ).
"The lines meeting the condition are respected.
"Note: The source table must have at least one sorted or hashed key.
"Here, the primary key is used
DATA(f1) = FILTER #( itab1 WHERE num >= 3 ).
DATA(f3) = FILTER #( tab USING KEY x WHERE comp = 4 ).
"USING KEY primary_key explicitly specified; same as above
DATA(f2) = FILTER #( itab1 USING KEY primary_key WHERE num >= 3 ).
"Filtering based on another table
DATA(f3) = FILTER #( tab IN filter_tab
                     WHERE comp = 3 ).
"EXCEPT addition
DATA(f3) = FILTER #( itab1 EXCEPT WHERE num >= 3 ).
DATA(f4) = FILTER #( itab1 EXCEPT USING KEY primary_key WHERE num >= 3 ).
"Secondary table key specified after USING KEY
DATA(f5) = FILTER #( itab2 USING KEY sec_key WHERE num >= 4 ).
DATA(f6) = FILTER #( itab2 EXCEPT USING KEY sec_key WHERE num >= 3 ).
"Note: In case of a hash key, exactly one comparison expression for each key component is allowed;
"only = as comparison operator possible.
DATA(f7) = FILTER #( itab3 WHERE num = 3 ).
"Using a filter table
"In the WHERE condition, the columns of source and filter table are compared. Those lines in the source table
"are used for which at least one line in the filter table meets the condition. EXCEPT and USING KEY are also possible.
DATA filter_tab1 TYPE SORTED TABLE OF i
WITH NON-UNIQUE KEY table_line.
DATA filter_tab2 TYPE STANDARD TABLE OF i
WITH EMPTY KEY
WITH UNIQUE SORTED KEY line COMPONENTS table_line.
DATA(f8) = FILTER #( itab1 IN filter_tab1 WHERE num = table_line ).
"EXCEPT addition
DATA(f9) = FILTER #( itab1 EXCEPT IN filter_tab1 WHERE num = table_line ).
"USING KEY is specified for the filter table
DATA(f10) = FILTER #( itab2 IN filter_tab2 USING KEY line WHERE num = table_line ).
"USING KEY is specified for the source table, including EXCEPT
DATA(f11) = FILTER #( itab2 USING KEY sec_key EXCEPT IN filter_tab2 WHERE num = table_line ).
```
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