How To Fix W8164 - A table element cannot be assigned a system field

SAP Error Message - Details

• Message type: E = Error

• Message class: W8 - Workflow: Expressions, data flow

• Message number: 164

• Message text: A table element cannot be assigned a system field

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• What is the cause and solution for SAP error message W8164 - A table element cannot be assigned a system field ?

  SAP Error Message:
  
  W8164 - A table element cannot be assigned a system field
  
  Cause:
  This warning occurs when you try to assign a system field (such as SY-... fields) directly to an element of an internal table in ABAP. System fields are special fields provided by the SAP runtime environment and are not designed to be stored in internal tables as table elements.
  For example, the following code would trigger this warning:
  DATA: itab TYPE TABLE OF sy-datum. " Invalid: sy-datum is a system field
  or
  DATA: itab TYPE TABLE OF some_structure.
  DATA: wa TYPE some_structure.
  
  wa-field = sy-datum.
  APPEND wa TO itab.
  If the structure contains a system field or you try to assign a system field directly to a table element, the system issues this warning.
  
  Explanation:
  
  System fields (SY- fields) are runtime fields that hold system information (like current date, time, user, etc.).
  They are not meant to be stored persistently or assigned directly to internal table elements.
  The ABAP runtime prevents this to avoid inconsistent or unintended behavior.
  
  
  Solution:
  
  Do not declare internal tables or work areas with system fields as components.
  Instead, declare your own variables or fields of appropriate data types and assign the values of system fields to these variables before appending or processing.
  If you need to store system field values in an internal table, create a custom field of the appropriate data type (e.g., D for date, T for time, C for character) and assign the system field value to this custom field.
  
  Example:
  TYPES: BEGIN OF ty_data,
           datum TYPE sy-datum, " Use the data type, not the system field itself
         END OF ty_data.
  
  DATA: itab TYPE TABLE OF ty_data,
        wa   TYPE ty_data.
  
  wa-datum = sy-datum.
  APPEND wa TO itab.
  
  Related Information:
  
  System fields (SY- fields) include fields like SY-DATUM, SY-UZEIT, SY-UNAME, etc.
  You can use system fields to get runtime information but should not use them as table element types.
  This warning is a syntax check warning and does not stop the program from running but should be corrected to avoid runtime issues.
  For more details, check SAP documentation on system fields and internal table declarations.
  
  
  Summary:
  
  
  
  Aspect
  Description
  
  
  
  
  Cause
  Attempting to assign or declare a system field (SY- field) as an internal table element.
  
  
  Solution
  Use a custom field with the same data type as the system field, then assign the system field value to it.
  
  
  Note
  System fields are runtime fields and should not be stored directly in internal tables.
  
  
  
  
  If you need further help with a specific code snippet causing this warning, feel free to share it!