/** * Derives an alias for a node, and invents a mangled identifier if it cannot. * * <p>Examples: * * <ul> * <li>Alias: "1 + 2 as foo" yields "foo" * <li>Identifier: "foo.bar.baz" yields "baz" * <li>Anything else yields "expr$<i>ordinal</i>" * </ul> * * @return An alias, if one can be derived; or a synthetic alias "expr$<i>ordinal</i>" if ordinal * >= 0; otherwise null */ public static String getAlias(SqlNode node, int ordinal) { switch (node.getKind()) { case AS: // E.g. "1 + 2 as foo" --> "foo" return ((SqlCall) node).getOperands()[1].toString(); case OVER: // E.g. "bids over w" --> "bids" return getAlias(((SqlCall) node).getOperands()[0], ordinal); case IDENTIFIER: // E.g. "foo.bar" --> "bar" return Util.last(((SqlIdentifier) node).names); default: if (ordinal < 0) { return null; } else { return SqlUtil.deriveAliasFromOrdinal(ordinal); } } }