anchor.diff:                            | expr ( ',' expr )*
                             )? 
                         ')'
  -                    | ( database_name '.' )? table_name )
  +                    | table_name )
    | ( ( K_NOT )? K_EXISTS )? '(' select_stmt ')'
    | K_CASE expr? ( K_WHEN expr K_THEN expr )+ ( K_ELSE expr )? K_END
    | raise_function
  
positive.code:  : any_name
   ;
  
  database_name
   : any_name
   ;
  
  table_name 
   : IDENTIFIER
   ;
  
negative.code:  ;
  
  table_or_subquery
   : table_name ( K_AS? table_alias )?
     ( K_INDEXED K_BY index_name
     | K_NOT K_INDEXED )?
   | '(' ( table_or_subquery ( ',' table_or_subquery )*
  