SQLExpr rightExpr = primary();
expr = new SQLBinaryOpExpr(expr, SQLBinaryOperator.IsNot, rightExpr);
} else if (identifierEquals("A")) {
lexer.nextToken();
accept(Token.SET);
expr = new OracleIsSetExpr(expr);
} else {
SQLExpr rightExpr = primary();
expr = new SQLBinaryOpExpr(expr, SQLBinaryOperator.Is, rightExpr);
}