enhance schema stat

src/main/java/com/alibaba/druid/sql/dialect/mysql/visitor/MySqlOutputVisitor.java

@@ -91,6 +91,10 @@ public class MySqlOutputVisitor extends SQLASTOutputVisitor implements MySqlASTV
     }
 
     public boolean visit(MySqlSelectQueryBlock select) {
+        if (select.getOrderBy() != null) {
+            select.getOrderBy().setParent(select);
+        }
+        
         print("SELECT ");
 
         if (SQLSetQuantifier.ALL == select.getDistionOption()) print("ALL ");

src/main/java/com/alibaba/druid/sql/dialect/oracle/visitor/OracleSchemaStatVisitor.java

@@ -212,7 +212,7 @@ public class OracleSchemaStatVisitor extends SchemaStatVisitor implements
 
 					// table == null时是SubQuery
 					if (table != null) {
-						fields.add(new Column(table, x.getName()));
+						columns.add(new Column(table, x.getName()));
 					}
 				}
 			}
@@ -236,7 +236,7 @@ public class OracleSchemaStatVisitor extends SchemaStatVisitor implements
 		String currentTable = currentTableLocal.get();
 
 		if (currentTable != null) {
-			fields.add(new Column(currentTable, x.getName()));
+			columns.add(new Column(currentTable, x.getName()));
 		}
 		return false;
 	}