db2 sql parser support hierarchical.

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

@@ -27,26 +27,28 @@ import com.alibaba.druid.sql.visitor.SQLASTVisitor;
 public class SQLSelectQueryBlock extends SQLObjectImpl implements SQLSelectQuery {
 
     protected int                       distionOption;
-    protected final List<SQLSelectItem> selectList = new ArrayList<SQLSelectItem>();
+    protected final List<SQLSelectItem> selectList      = new ArrayList<SQLSelectItem>();
 
     protected SQLTableSource            from;
     protected SQLExprTableSource        into;
     protected SQLExpr                   where;
+
+    // for oracle & oceanbase
+    protected SQLExpr                   startWith;
+    protected SQLExpr                   connectBy;
+    protected boolean                   prior           = false;
+    protected boolean                   noCycle         = false;
+    protected SQLOrderBy                orderBySiblings;
+
     protected SQLSelectGroupByClause    groupBy;
     protected SQLOrderBy                orderBy;
-    protected boolean                   parenthesized = false;
-    protected boolean                   forUpdate     = false;
-    protected boolean                   noWait        = false;
+    protected boolean                   parenthesized   = false;
+    protected boolean                   forUpdate       = false;
+    protected boolean                   noWait          = false;
     protected SQLExpr                   waitTime;
 
     protected SQLLimit                  limit;
 
-    // for oracle & oceanbase
-    protected SQLExpr startWith;
-    protected SQLExpr connectBy;
-    protected boolean prior   = false;
-    protected boolean noCycle = false;
-
     public SQLSelectQueryBlock(){
 
     }
@@ -100,6 +102,17 @@ public class SQLSelectQueryBlock extends SQLObjectImpl implements SQLSelectQuery
         this.orderBy = orderBy;
     }
 
+    public SQLOrderBy getOrderBySiblings() {
+        return orderBySiblings;
+    }
+
+    public void setOrderBySiblings(SQLOrderBy orderBySiblings) {
+        if (orderBySiblings != null) {
+            orderBySiblings.setParent(this);
+        }
+        this.orderBySiblings = orderBySiblings;
+    }
+
     public int getDistionOption() {
         return this.distionOption;
     }

src/main/java/com/alibaba/druid/sql/dialect/db2/parser/DB2SelectParser.java

@@ -76,6 +76,8 @@ public class DB2SelectParser extends SQLSelectParser {
 
         parseWhere(queryBlock);
 
+        parseHierachical(queryBlock);
+
         parseGroupBy(queryBlock);
         
         if (lexer.token() == Token.ORDER) {

src/main/java/com/alibaba/druid/sql/visitor/SQLASTOutputVisitor.java

@@ -1089,6 +1089,8 @@ public class SQLASTOutputVisitor extends SQLASTVisitorAdapter implements Paramet
             where.accept(this);
         }
 
+        printHierarchical(x);
+
         if (x.getGroupBy() != null) {
             println();
             x.getGroupBy().accept(this);

src/test/java/com/alibaba/druid/bvt/sql/db2/DB2SelectTest_hierarchical_1.java

@@ -0,0 +1,73 @@
+/*
+ * Copyright 1999-2017 Alibaba Group Holding Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.alibaba.druid.bvt.sql.db2;
+
+import com.alibaba.druid.sql.MysqlTest;
+import com.alibaba.druid.sql.SQLUtils;
+import com.alibaba.druid.sql.ast.SQLStatement;
+import com.alibaba.druid.sql.visitor.SchemaStatVisitor;
+import com.alibaba.druid.util.JdbcConstants;
+
+import java.util.List;
+
+public class DB2SelectTest_hierarchical_1 extends MysqlTest {
+    protected final String dbType = JdbcConstants.DB2;
+
+    public void test_0() throws Exception {
+        String sql = "SELECT last_name, employee_id, manager_id, LEVEL\n" +
+                "      FROM employees\n" +
+                "      START WITH employee_id = 100\n" +
+                "      CONNECT BY PRIOR employee_id = manager_id\n" +
+                "      ORDER SIBLINGS BY last_name;"; //
+
+        List<SQLStatement> stmtList = SQLUtils.parseStatements(sql, dbType);
+        SQLStatement stmt = stmtList.get(0);
+
+        {
+            String result = SQLUtils.toSQLString(stmt, dbType);
+            assertEquals("SELECT last_name, employee_id, manager_id, LEVEL\n" +
+                    "FROM employees\n" +
+                    "START WITH employee_id = 100\n" +
+                    "CONNECT BY PRIOR employee_id = manager_id\n" +
+                    "ORDER SIBLINGS BY last_name", result);
+        }
+        {
+            String result = SQLUtils.toSQLString(stmt, dbType, SQLUtils.DEFAULT_LCASE_FORMAT_OPTION);
+            assertEquals("select last_name, employee_id, manager_id, LEVEL\n" +
+                    "from employees\n" +
+                    "start with employee_id = 100\n" +
+                    "connect by prior employee_id = manager_id\n" +
+                    "order siblings by last_name", result);
+        }
+
+        assertEquals(1, stmtList.size());
+
+        SchemaStatVisitor visitor = SQLUtils.createSchemaStatVisitor(dbType);
+        stmt.accept(visitor);
+
+        System.out.println("Tables : " + visitor.getTables());
+        System.out.println("fields : " + visitor.getColumns());
+        System.out.println("coditions : " + visitor.getConditions());
+        System.out.println("orderBy : " + visitor.getOrderByColumns());
+
+        assertEquals(1, visitor.getTables().size());
+        assertEquals(4, visitor.getColumns().size());
+        assertEquals(0, visitor.getConditions().size());
+
+        // assertTrue(visitor.getTables().containsKey(new TableStat.Name("t_basic_store")));
+
+    }
+}