-20180   COLUMN column-name IN TABLE table-name CANNOT BE ALTERED AS SPECIFIED

The column could not be altered.

column-name

The name of the column.

table-name

The name of the table that contains the column.

Possible reasons for this error include a violation of one of the following restrictions:

• ALTER COLUMN cannot be specified in an ALTER TABLE statement if any of the following conditions are true:
  • The table is defined with DATA CAPTURE CHANGES.
  • The column is involved in a referential integrity constraint (either as part of the parent key or foreign key).
  • The column is involved in an extended index definition.
  • The column has a field procedure defined.
  • The column is an identity column or a row change timestamp column.
  • The column is a LOB column that is referenced in an expression-based index, and the change would reduce the inline length of the column.
  • The table is defined as a history table or system-period temporal table.
  • The column is defined as ROW BEGIN, ROW END, or TRANSACTION START ID.
  • The column is involved in a hash key definition.
• ALTER COLUMN cannot be specified in an ALTER TABLE statement with either a SET NOT NULL or SET DATA TYPE clause if the column is defined as part of a period definition.
• ALTER COLUMN cannot be specified in an ALTER TABLE statement with a DROP DEFAULT or SET DATA TYPE clause if both of the following conditions are true:
  • The table is defined with DATA CAPTURE CHANGES.
  • The subsystem parameter RESTRICT_ALT_COL_FOR_DCC is set to YES.
• SET DATA TYPE cannot be specified in an ALTER TABLE statement if any of the following conditions are true:
  • The table is a materialized query table.
  • The table has an edit procedure or valid procedure.
  • The column is involved in an extended index definition.
  • VARBINARY was specified as the target data type and the column is defined with the following attributes:
    • As CHAR FOR BIT DATA, VARCHAR FOR BIT DATA, or BINARY
    • With the DESC attribute in an index