How To Fix SDDL_PARSER_MSG018 - Number of fields in selection lists in unions must be the same

SAP Error Message - Details

• Message type: E = Error

• Message class: SDDL_PARSER_MSG - Message Class for DDL Parser

• Message number: 018

• Message text: Number of fields in selection lists in unions must be the same

Self-Explanatory Message

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Smart SAP Assistant

• What is the cause and solution for SAP error message SDDL_PARSER_MSG018 - Number of fields in selection lists in unions must be the same ?

  The SAP error message SDDL_PARSER_MSG018 indicates that there is a mismatch in the number of fields in the selection lists of a union operation in your ABAP program or query. This error typically occurs when you are trying to combine the results of two or more SELECT statements using a UNION, but the number of fields (columns) in each SELECT statement does not match.
  Cause:
  The primary cause of this error is that the SELECT statements involved in the UNION do not have the same number of fields. For a UNION operation to be valid, each SELECT statement must return the same number of columns, and the corresponding columns must have compatible data types.
  Solution:
  To resolve this error, you should:
  
  
  Check the SELECT Statements: Review the SELECT statements that are part of the UNION. Ensure that each SELECT statement has the same number of fields.
  
  
  Align the Number of Fields: If one SELECT statement has more fields than another, you need to either:
  
  Remove the extra fields from the SELECT statement that has more fields.
  Add dummy fields (e.g., NULL values or default values) to the SELECT statement that has fewer fields to match the number of fields in the other SELECT statements.
  
  
  
  Ensure Data Type Compatibility: Make sure that the data types of the corresponding fields in each SELECT statement are compatible. For example, if one SELECT statement returns a string and another returns an integer, you may need to cast or convert the data types to ensure compatibility.
  
  
  Example:
  Here’s a simple example to illustrate the issue:
  DATA: lt_result TYPE TABLE OF your_structure.
  
  SELECT field1, field2 FROM table1 INTO TABLE lt_result.
  SELECT field1, field2, field3 FROM table2 INTO TABLE lt_result.  " This will cause the error
  To fix the error, you can modify the second SELECT statement to match the number of fields:
  DATA: lt_result TYPE TABLE OF your_structure.
  
  SELECT field1, field2 FROM table1 INTO TABLE lt_result.
  SELECT field1, field2, NULL AS field3 FROM table2 INTO TABLE lt_result.  " Now it matches
  Related Information:
  
  UNION vs. UNION ALL: Remember that UNION removes duplicate records, while UNION ALL includes all records. The same rules apply regarding the number of fields.
  Performance Considerations: Using UNION can have performance implications, especially with large datasets. Consider whether you need to use UNION or if there are alternative approaches.
  Debugging: If you are unsure which SELECT statement is causing the issue, you can comment out one SELECT statement at a time to isolate the problem.
  
  By ensuring that all SELECT statements in your UNION have the same number of fields and compatible data types, you should be able to resolve the SDDL_PARSER_MSG018 error.