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references/abap-programming.md
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references/abap-programming.md
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# SAP ABAP Programming Reference
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**Source**: [https://codezentrale.de/category/sap/sap-abap/](https://codezentrale.de/category/sap/sap-abap/)
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**Language**: Translated from German
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This reference covers ABAP programming patterns relevant to SAP HANA development.
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---
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## Table of Contents
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1. [SQL Operations](#sql-operations)
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2. [Internal Tables](#internal-tables)
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3. [String Operations](#string-operations)
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4. [JSON Processing](#json-processing)
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5. [XML Processing](#xml-processing)
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6. [Regular Expressions](#regular-expressions)
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7. [Exception Handling](#exception-handling)
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8. [Performance Optimization](#performance-optimization)
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---
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## SQL Operations
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### Open SQL
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#### Common Table Expressions (CTE)
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```abap
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WITH
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+cte1 AS ( SELECT * FROM table1 WHERE condition ),
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+cte2 AS ( SELECT * FROM +cte1 WHERE condition2 )
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SELECT * FROM +cte2 INTO TABLE @DATA(lt_result).
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```
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#### String Aggregation
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```abap
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SELECT STRING_AGG( field, ',' ) AS aggregated
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FROM table
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INTO @DATA(lv_result).
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```
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#### Global Temporary Tables (GTT)
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```abap
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" Use GTT for intermediate data storage
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```
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### Performance Comparison
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| Method | Performance |
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|--------|-------------|
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| RANGE clause | ~0.086 seconds |
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| FOR ALL ENTRIES | ~0.073 seconds |
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| JOIN | ~0.012 seconds (fastest) |
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**Best Practice**: Use JOINs instead of FOR ALL ENTRIES when possible.
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### AMDP (ABAP Managed Database Procedures)
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Convert RANGES to WHERE clause for AMDP:
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```abap
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" Using cl_shdb_seltab
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DATA(lv_where) = cl_shdb_seltab=>combine_seltabs(
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it_named_seltabs = VALUE #(
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( name = 'FIELD' dref = REF #( lr_range ) )
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)
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)->sql_where_condition( ).
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```
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---
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## Internal Tables
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### TABLE_LINE Pseudo-Component
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```abap
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" Access complete row without structure
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DATA(lv_vbeln) = it_vbeln[ table_line = '2345678901' ].
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```
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### REDUCE Operator
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```abap
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" Sum values
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DATA(lv_sum) = REDUCE decfloat34(
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INIT sum = CONV decfloat34( 0 )
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FOR wa IN it_costs
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NEXT sum = sum + wa-amount ).
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```
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### OPTIONAL Clause
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```abap
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" Avoid exceptions for missing entries
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DATA(ls_person) = VALUE #( it_persons[ name = 'John' ] OPTIONAL ).
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```
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### DEFAULT VALUE
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```abap
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" Provide fallback value
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DATA(ls_person) = VALUE #(
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it_persons[ name = 'John' ]
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DEFAULT VALUE #( name = '<empty>' age = -1 )
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).
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```
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### BASE Operator
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```abap
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" Prepend existing data
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it_result = VALUE #( BASE it_existing ( field = 'new' ) ).
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```
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### Line Index
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```abap
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" Get index without exceptions
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DATA(lv_idx) = line_index( itab[ col = '123' ] ).
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```
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### Search Operations
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```abap
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" Case-insensitive search
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FIND 'pattern' IN TABLE it_data IGNORING CASE.
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" All occurrences
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FIND ALL OCCURRENCES OF 'pattern' IN it_data
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RESULTS DATA(lt_results).
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```
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---
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## String Operations
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### Substring Extraction
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```abap
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" Offset and length syntax
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DATA(lv_first) = CONV string( lv_string+0(1) ).
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DATA(lv_middle) = CONV string( lv_string+5(3) ).
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```
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### Transliteration
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```abap
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" Convert special characters
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CALL FUNCTION 'SCP_REPLACE_STRANGE_CHARS'
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EXPORTING
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intext = lv_input
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IMPORTING
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outtext = lv_output.
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" Result: ÄÖÜ → AeOeUe
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```
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### Codepage Conversion
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```abap
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" SAP codepage to HTTP encoding
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DATA(lv_encoding) = cl_abap_codepage=>sap_codepage(
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http_encoding = 'UTF-8' ).
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```
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### Pattern Matching (CP Operator)
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```abap
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" Wildcard matching
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IF lv_string CP '*-*'. " Contains dash
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IF lv_string CP '+++*'. " Three+ characters
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```
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### Message Text Splitting
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```abap
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" Distribute text across message fields
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cl_message_helper=>set_msg_vars_for_clike(
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EXPORTING i_text = lv_long_text ).
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" Access via sy-msgv1, sy-msgv2, sy-msgv3, sy-msgv4
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```
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---
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## JSON Processing
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### ABAP to JSON
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```abap
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" Using xco_cp_json (modern)
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DATA(lv_json) = xco_cp_json=>data->from_abap( ls_data )->to_string( ).
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" Using /ui2/cl_json
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DATA(lv_json) = /ui2/cl_json=>serialize(
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data = ls_data
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pretty_name = /ui2/cl_json=>pretty_mode-camel_case ).
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```
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### JSON to ABAP
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```abap
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" Using xco_cp_json
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xco_cp_json=>data->from_string( lv_json )->apply(
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VALUE #( ( xco_cp_json=>transformation->boolean_to_abap_bool )
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( xco_cp_json=>transformation->pascal_case_to_underscore ) )
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)->write_to( REF #( ls_data ) ).
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" Using /ui2/cl_json
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/ui2/cl_json=>deserialize(
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EXPORTING json = lv_json
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CHANGING data = ls_data ).
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```
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### Internal Table to JSON
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```abap
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" Using transformation
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CALL TRANSFORMATION id
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SOURCE values = it_data
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RESULT XML DATA(lv_json).
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```
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---
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## XML Processing
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### XML to Internal Table
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```abap
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" Using cl_xml_document
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DATA(lo_xml) = cl_xml_document=>create( ).
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lo_xml->import_from_file( lv_filename ).
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CALL FUNCTION 'SMUM_XML_PARSE'
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EXPORTING
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xml_input = lo_xml->get_document_xml_string( )
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TABLES
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return = lt_return
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xml_table = lt_xml_data.
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```
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### Display XML in Browser
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```abap
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cl_soap_xml_helper=>xml_show(
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xml_xstring = lv_xml_xstring ).
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```
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### ABAP to XML
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```abap
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DATA(lv_xml) = cl_proxy_xml_transform=>abap_to_xml_xstring(
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abap_data = ls_structure ).
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```
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---
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## Regular Expressions
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### Replace Non-Alphanumeric
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```abap
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REPLACE ALL OCCURRENCES OF REGEX '[^\w]+' IN lv_str WITH '_'.
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```
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### Using cl_abap_matcher
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```abap
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DATA(lo_matcher) = cl_abap_matcher=>create(
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pattern = '<placeholder>'
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text = lv_text
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ignore_case = abap_true ).
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IF lo_matcher->replace_all( ' and ' ) > 0.
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DATA(lv_result) = lo_matcher->text.
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ENDIF.
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```
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### Extract Submatches
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```abap
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DATA(lo_matcher) = cl_abap_matcher=>create(
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pattern = '^/category/([0-9]+)/item/([0-9]+)$'
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text = '/category/12345/item/12' ).
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IF lo_matcher->match( ).
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DATA(lv_category) = lo_matcher->get_submatch( 1 ). " 12345
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DATA(lv_item) = lo_matcher->get_submatch( 2 ). " 12
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ENDIF.
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```
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### Remove HTML Tags
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```abap
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DATA(lo_matcher) = cl_abap_matcher=>create(
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pattern = '<([!A-Za-z][A-Za-z0-9]*)|</([A-Za-z][A-Za-z0-9]*)>'
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text = lv_html ).
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lo_matcher->replace_all( '' ).
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```
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### Common Patterns
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| Pattern | Purpose |
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|---------|---------|
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| `[^\w]+` | Non-alphanumeric characters |
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| `\s` | Whitespace |
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| `[0-9]` | Digits |
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| `^(AA\|BB).*$` | String prefix match |
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| `\d{5}` | German postal code |
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---
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## Exception Handling
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### TRY...CATCH Block
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```abap
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TRY.
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" Risky operation
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DATA(lv_result) = 1 / 0.
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CATCH cx_sy_zerodivide INTO DATA(lx_error).
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" Handle exception
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DATA(lv_msg) = lx_error->get_text( ).
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ENDTRY.
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```
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### Custom Exception Class
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```abap
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CLASS lcx_custom_error DEFINITION
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INHERITING FROM cx_static_check.
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PUBLIC SECTION.
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DATA mv_custom_field TYPE string.
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METHODS constructor
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IMPORTING
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iv_custom_field TYPE string OPTIONAL.
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ENDCLASS.
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" Raising
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RAISE EXCEPTION TYPE lcx_custom_error
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EXPORTING iv_custom_field = 'Error details'.
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```
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### Using CX_T100_MSG
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```abap
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CLASS lcx_message DEFINITION
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INHERITING FROM cx_t100_msg.
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PUBLIC SECTION.
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CONSTANTS:
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BEGIN OF error_occurred,
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msgid TYPE symsgid VALUE 'ZMSG',
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msgno TYPE symsgno VALUE '001',
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attr1 TYPE scx_attrname VALUE 'MV_ATTR1',
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END OF error_occurred.
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ENDCLASS.
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```
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---
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## Performance Optimization
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### Field Symbols vs. References
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```abap
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" Faster: Field symbols
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LOOP AT it_data ASSIGNING FIELD-SYMBOL(<ls_data>).
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<ls_data>-field = 'value'.
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ENDLOOP.
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" Slower: References
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LOOP AT it_data REFERENCE INTO DATA(lr_data).
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lr_data->field = 'value'.
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ENDLOOP.
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```
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### COLLECT for Deduplication
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```abap
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" Fastest approach - uses internal hash table
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COLLECT ls_line INTO it_aggregated.
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```
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### Table Copy Efficiency
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```abap
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" Most efficient: Direct assignment
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it_target = it_source.
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" Also efficient: CORRESPONDING
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it_target = CORRESPONDING #( it_source ).
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```
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### SQL Best Practices
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1. Use JOINs instead of FOR ALL ENTRIES
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2. Use WHERE conditions early
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3. Limit result sets with UP TO n ROWS
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4. Use indexes appropriately
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5. Avoid SELECT * when possible
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---
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## Useful Classes Reference
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| Class | Purpose |
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|-------|---------|
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| `cl_abap_matcher` | Regular expressions |
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| `cl_abap_codepage` | Codepage conversion |
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| `/ui2/cl_json` | JSON serialization |
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| `xco_cp_json` | Modern JSON handling |
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| `cl_xml_document` | XML processing |
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| `cl_salv_table` | ALV display |
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| `cl_gui_alv_grid` | ALV grid control |
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| `cl_abap_typedescr` | Runtime type info |
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| `cl_shdb_seltab` | RANGES to WHERE |
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---
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*Source: [https://codezentrale.de/category/sap/sap-abap/*](https://codezentrale.de/category/sap/sap-abap/*)
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