bug fixed for sql parser.

src/main/java/com/alibaba/druid/sql/ast/statement/SQLAlterTableStatement.java

@@ -40,6 +40,9 @@ public class SQLAlterTableStatement extends SQLStatementImpl implements SQLDDLSt
     private boolean                 upgradePatiting         = false;
     private Map<String, SQLObject>  tableOptions            = new LinkedHashMap<String, SQLObject>();
 
+    // odps
+    private boolean                 mergeSmallFiles         = false;
+
     public SQLAlterTableStatement(){
 
     }
@@ -88,6 +91,14 @@ public class SQLAlterTableStatement extends SQLStatementImpl implements SQLDDLSt
         this.invalidateGlobalIndexes = invalidateGlobalIndexes;
     }
 
+    public boolean isMergeSmallFiles() {
+        return mergeSmallFiles;
+    }
+
+    public void setMergeSmallFiles(boolean mergeSmallFiles) {
+        this.mergeSmallFiles = mergeSmallFiles;
+    }
+
     public List<SQLAlterTableItem> getItems() {
         return items;
     }

src/main/java/com/alibaba/druid/sql/ast/statement/SQLSelectQueryBlock.java

@@ -65,6 +65,9 @@ public class SQLSelectQueryBlock extends SQLObjectImpl implements SQLSelectQuery
     }
 
     public void setGroupBy(SQLSelectGroupByClause groupBy) {
+        if (groupBy != null) {
+            groupBy.setParent(this);
+        }
         this.groupBy = groupBy;
     }
 
@@ -113,6 +116,9 @@ public class SQLSelectQueryBlock extends SQLObjectImpl implements SQLSelectQuery
     }
 
     public void setFrom(SQLTableSource from) {
+        if (from != null) {
+            from.setParent(this);
+        }
         this.from = from;
     }