anchor.diff:  
   DROP_ASSERTION_STATEMENT ::=
   	DROP ASSERTION CONSTRAINT_NAME
  -
  -SQL_DATA_STATEMENT ::=
  -	  OPEN_STATEMENT
  +*/
  +
  +SQL_DATA_STATEMENT 
  +/*
  +	: OPEN_STATEMENT
   	| FETCH_STATEMENT
   	| CLOSE_STATEMENT
  -	| SELECT_STATEMENT:_SINGLE_ROW
  +*/
  +	: SELECT_STATEMENT_SINGLE_ROW
  +/*
   	| SQL_DATA_CHANGE_STATEMENT
  -
  +*/
  +	;
  +
  +/*
   OPEN_STATEMENT ::=
   	OPEN CURSOR_NAME
   
  
positive.code: 	| LEFT_PAREN NON_JOIN_QUERY_EXPRESSION RIGHT_PAREN
  	;
  
  SIMPLE_TABLE ::=
  	  QUERY_SPECIFICATION
  /*
  	| TABLE_VALUE_CONSTRUCTOR
  	| EXPLICIT_TABLE
  
negative.code: 	;
  
  /*
  	| INTERVAL | 
  */
  
  INTO
  	: I N T O
  	;
  
  /*
  	 | IS
  	| ISOLATION
  	| JOIN
  	| KEY
  