Oracle forms 10g to restrict the Query in the Form based on column value

DECLARE
  v_def_where   VARCHAR2(2000) := Get_Block_Property('XXFUJ_PM_DETAILS',DEFAULT_WHERE);
  v_new_where   VARCHAR2(2000);
  --v_condition varchar2(100) := 'EMPLOYEE';
 
BEGIN
  v_new_where := 'CATEGORY = ''MANAGER''';
  Set_Block_Property('XXFUJ_PM_DETAILS',DEFAULT_WHERE, v_new_where);
  Execute_Query;
  -- Now reset the DEFAULT_WHERE back to it's original value.
  --Set_Block_Property('TRANS',DEFAULT_WHERE, v_def_where);
END;

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CATEGORY = ''MANAGER''            --two single quotes

<column_name> = ''<TEXT>''