create unique index LIST_ITEM_ENTRY_NO_UNIQ
on LIST_ITEM (case status when 'cancel' then null else LIST_KEY end,
              case status when 'cancel' then null else ENTRY_NO end);

alter table LIST_ITEM add constraint LIST_ITEM_ENTRY_NO_UNIQ
unique (LIST_KEY,ENTRY_NO) deferrable initially deferred;

alter table LIST_ITEM add constraint LIST_ITEM_ENTRY_NO_UNIQ
unique (case STATUS when 'cancel' then null else LIST_KEY end,
        case STATUS when 'cancel' then null else ENTRY_NO end)
deferrable initially deferred;

CREATE INDEX ::=

    CREATE [ UNIQUE | BITMAP ] INDEX [ schema. ]index
      ON { cluster_index_clause
         | table_index_clause
         | bitmap_join_index_clause
         } ;

table_index_clause ::=

    [ schema. ]table [ t_alias ]
    (index_expr [ ASC | DESC ]
      [, index_expr [ ASC | DESC ] ]...)
    [ index_properties ]

index_expr ::= { column | column_expression }

ALTER TABLE ::=
ALTER TABLE [ schema. ]table
  [ alter_table_properties
  | column_clauses
  | constraint_clauses
  | alter_table_partitioning
  | alter_external_table_clauses
  | move_table_clause
  ]
  [ enable_disable_clause
  | { ENABLE | DISABLE }
    { TABLE LOCK | ALL TRIGGERS }
    [ enable_disable_clause
    | { ENABLE | DISABLE }
      { TABLE LOCK | ALL TRIGGERS }
    ]...
  ] ;

constraint_clauses ::=
{ ADD { out_of_line_constraint
        [ out_of_line_constraint ]...
      | out_of_line_REF_constraint
      }
| MODIFY { CONSTRAINT constraint
         | PRIMARY KEY
         | UNIQUE (column [, column ]...)
         }
         constraint_state
| RENAME CONSTRAINT old_name TO new_name
| drop_constraint_clause
}

out_of_line_constraint ::=
[ CONSTRAINT constraint_name ]
{ UNIQUE (column [, column ]...)
| PRIMARY KEY (column [, column ]...)
| FOREIGN KEY (column [, column ]...)
     references_clause
| CHECK (condition)
}
[ constraint_state ]