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Duplicate Unique Keys

When rows are inserted into internal tables with a unique primary key or unique secondary key, duplicates can occur with respect to one or more of these keys. Depending on whether the insert takes place as a single record operation or a mass operation, the ABAP runtime environment responds as follows to an attempt to insert an entry with duplicate key values:

  • First, it checks whether duplicate key values would occur with respect to the primary key. The system behavior is as follows depending on the operation:
  • When single rows are inserted using the variant


    duplicate with respect to the primary key are ignored and sy-subrc is set to 4. This is often used to filter out duplicates when the table is constructed.
  • A check is then made to see whether duplicate key values would occur with respect to any existing unique secondary keys. If this is the case,
  • an exception of the class CX_SY_ITAB_DUPLICATE_KEY is raised for the statements INSERT and APPEND, if the operation is a single record operation.
  • For all other insert and assignment operations, particularly for all mass operations, the runtime error ITAB_DUPLICATE_KEY occurs.

Other versions: 7.31 | 7.40 | 7.54