* Otherwise, it will return NULL.
*/
public String checkAndGetIfAliasedColumn(String name) {
Expr expr = getExpr(name);
if (expr != null && expr.getType() == OpType.Column) {
ColumnReferenceExpr column = (ColumnReferenceExpr) expr;
if (!column.getCanonicalName().equals(name)) {
return column.getCanonicalName();
}
}
return null;
}