/** Converts an expression "expr" into "expr AS alias". */
public static SqlNode addAlias(SqlNode expr, String alias) {
final SqlParserPos pos = expr.getParserPosition();
final SqlIdentifier id = new SqlIdentifier(alias, pos);
return SqlStdOperatorTable.AS.createCall(pos, expr, id);
}
/**
* Returns a node that can be included in the FROM clause or a JOIN. It has an alias that is
* unique within the query. The alias is implicit if it can be derived using the usual rules
* (For example, "SELECT * FROM emp" is equivalent to "SELECT * FROM emp AS emp".)
*/
public SqlNode asFrom() {
if (neededAlias != null) {
return SqlStdOperatorTable.AS.createCall(POS, node, new SqlIdentifier(neededAlias, POS));
}
return node;
}