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05_Constructor_Expressions.md
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@@ -1126,68 +1126,176 @@ ENDCASE.
## FILTER
- The
`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).
[`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 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.
existing internal table based on conditions specified in a `WHERE` condition. 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: 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. |
- The source table must have at least one [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") for accessing. If the table does not have such a primary table key, 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.
- Syntax options for the using the table key (i.e. specifying its components):
- Using the [primary table key](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenprimary_table_key_glosry.htm) without the `USING KEY` addition
- Using the default name `primary_key` for the primary key with `USING KEY`
- Using the secondary table key with `USING KEY`
- Notes on the `WHERE` condition:
- The conditions for the table key components can be specified as follows:
- Hash keys: Only the comparison operator `=` is allowed
- Sorted key: `=`/`EQ`, `<>`/`NE`, `<`/`LT`, `>`/`GT`, `<=`/`LE`, `>=`/`GE`
- Multiple comparisons can be combined using `AND`; boolean operators such as `NOT` or `OR` cannot be specified.
- Notes on the filter table:
- The line types of the source and filter table need not be identical.
- Refer to the [documentation](https://help.sap.com/doc/abapdocu_cp_index_htm/CLOUD/en-US/index.htm?file=abenconstructor_expr_filter_table.htm) for all syntax options. For example, depending on where `USING KEY` is specified, the table key is specified for the source or filter table for the access.
- Notes on the `EXCEPT` addition: The specification of `EXCEPT` means that those lines of the table are used that do not meet the condition specified in the `WHERE` condition. Therefore, if `EXCEPT` is not specified, the lines of the table are used that meet the condition.
Examples:
```abap
"FILTER and 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.
"Internal tables to work with in the example
TYPES: BEGIN OF fi_str,
a TYPE i,
b TYPE c LENGTH 3,
c TYPE c LENGTH 3,
END OF fi_str.
"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 fi_tab1 TYPE SORTED TABLE OF fi_str WITH NON-UNIQUE KEY a.
DATA fi_tab2 TYPE STANDARD TABLE OF fi_str WITH NON-UNIQUE SORTED KEY sec_key COMPONENTS a.
DATA fi_tab3 TYPE HASHED TABLE OF fi_str WITH UNIQUE KEY a.
DATA fi_tab4 TYPE STANDARD TABLE OF fi_str WITH UNIQUE HASHED KEY sec_hash_key COMPONENTS a b.
"USING KEY primary_key explicitly specified; same as above
DATA(f2) = FILTER #( itab1 USING KEY primary_key WHERE num >= 3 ).
"Populating internal tables with demo data
fi_tab1 = VALUE #( ( a = 1 b = 'aaa' c = 'abc' )
( a = 2 b = 'bbb' c = 'def' )
( a = 3 b = 'ccc' c = 'hij' )
( a = 4 b = 'ddd' c = 'klm' )
( a = 5 b = 'eee' c = 'nop' ) ).
"EXCEPT addition
DATA(f3) = FILTER #( itab1 EXCEPT WHERE num >= 3 ).
DATA(f4) = FILTER #( itab1 EXCEPT USING KEY primary_key WHERE num >= 3 ).
fi_tab2 = fi_tab1.
fi_tab3 = fi_tab1.
fi_tab4 = fi_tab1.
"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 ).
"---------------- Basic form: Filtering using single values ----------------
"Syntax options for using a WHERE condition and the table key
"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 the primary table key without specifying USING KEY
DATA(f1) = FILTER #( fi_tab1 WHERE a >= 4 ).
"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.
*A B C
*4 ddd klm
*5 eee nop
DATA filter_tab1 TYPE SORTED TABLE OF i
WITH NON-UNIQUE KEY table_line.
"Using the primary table key by specifying the default name primary_key
"and specifying USING KEY; the result in the example is the same as above
DATA(f2) = FILTER #( fi_tab1 USING KEY primary_key WHERE a >= 4 ).
DATA filter_tab2 TYPE STANDARD TABLE OF i
WITH EMPTY KEY
WITH UNIQUE SORTED KEY line COMPONENTS table_line.
*A B C
*4 ddd klm
*5 eee nop
DATA(f8) = FILTER #( itab1 IN filter_tab1 WHERE num = table_line ).
"Using the secondary table key by specifying its name and USING KEY
DATA(f3) = FILTER #( fi_tab2 USING KEY sec_key WHERE a < 3 ).
"EXCEPT addition
DATA(f9) = FILTER #( itab1 EXCEPT IN filter_tab1 WHERE num = table_line ).
*A B C
*1 aaa abc
*2 bbb def
"USING KEY is specified for the filter table
DATA(f10) = FILTER #( itab2 IN filter_tab2 USING KEY line WHERE num = table_line ).
"Note: When using a table with hash key, only the comparison operator =
"can be used in the WHERE clause
"The example uses the primary table key, which is a hash key.
DATA(f4) = FILTER #( fi_tab3 WHERE a = 3 ).
"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 ).
*A B C
*3 ccc hij
"The example table used in the following example has two components specified
"for the table key. The key must be specified in full listing all components
"and using AND.
DATA(f5) = FILTER #( fi_tab4 USING KEY sec_hash_key WHERE a = 3 AND b = 'ccc' ).
*A B C
*3 ccc hij
"Examples with the EXCEPT addition
DATA(f6) = FILTER #( fi_tab1 EXCEPT WHERE a >= 4 ).
*A B C
*1 aaa abc
*2 bbb def
*3 ccc hij
DATA(f7) = FILTER #( fi_tab1 EXCEPT USING KEY primary_key WHERE a >= 4 ).
*A B C
*1 aaa abc
*2 bbb def
*3 ccc hij
"Secondary table key specified after USING KEY
DATA(f8) = FILTER #( fi_tab2 USING KEY sec_key WHERE a <= 2 ).
*A B C
*1 aaa abc
*2 bbb def
DATA(f9) = FILTER #( fi_tab2 EXCEPT USING KEY sec_key WHERE a >= 4 ).
*A B C
*1 aaa abc
*2 bbb def
*3 ccc hij
DATA(f10) = FILTER #( fi_tab4 EXCEPT USING KEY sec_hash_key WHERE a = 3 AND b = 'ccc' ).
*A B C
*1 aaa abc
*2 bbb def
*4 ddd klm
*5 eee nop
"---------------- Basic form: Filtering 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.
"The following examples use simple tables with elementary line types. Note
"that the line types of the tables in a FILTER epxression need not be identical.
"Declaring and filling filter tables
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.
filter_tab1 = VALUE #( ( 3 ) ( 5 ) ).
filter_tab2 = filter_tab1.
"No further additions specified
DATA(f11) = FILTER #( fi_tab1 IN filter_tab1 WHERE a = table_line ).
*A B C
*3 ccc hij
*5 eee nop
"Specifying EXCEPT addition
DATA(f12) = FILTER #( fi_tab1 EXCEPT IN filter_tab1 WHERE a = table_line ).
*A B C
*1 aaa abc
*2 bbb def
*4 ddd klm
"Specifying USING KEY for the filter table
DATA(f13) = FILTER #( fi_tab2 IN filter_tab2 USING KEY line WHERE a = table_line ).
*A B C
*3 ccc hij
*5 eee nop
"Specifying USING KEY for the source table, including EXCEPT
DATA(f14) = FILTER #( fi_tab2 USING KEY sec_key EXCEPT IN filter_tab2 WHERE a = table_line ).
*A B C
*1 aaa abc
*2 bbb def
*4 ddd klm
```
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