fix issue #471 DB2数据库SQL带ORDER BY的分页查询生成的语句不对

src/main/java/com/alibaba/druid/sql/dialect/db2/visitor/DB2OutputVisitor.java

@@ -15,6 +15,9 @@
  */
 package com.alibaba.druid.sql.dialect.db2.visitor;
 
+import com.alibaba.druid.sql.ast.SQLObject;
+import com.alibaba.druid.sql.ast.SQLOrderBy;
+import com.alibaba.druid.sql.ast.statement.SQLSelect;
 import com.alibaba.druid.sql.ast.statement.SQLSelectQueryBlock;
 import com.alibaba.druid.sql.dialect.db2.ast.stmt.DB2SelectQueryBlock;
 import com.alibaba.druid.sql.dialect.db2.ast.stmt.DB2ValuesStatement;
@@ -31,12 +34,26 @@ public class DB2OutputVisitor extends SQLASTOutputVisitor implements DB2ASTVisit
         this.visit((SQLSelectQueryBlock) x);
 
         if (x.getFirst() != null) {
+
+            //order by 语句必须在FETCH FIRST ROWS ONLY之前
+            SQLObject parent= x.getParent();
+            if(parent instanceof SQLSelect)
+            {
+                SQLOrderBy orderBy= ((SQLSelect) parent).getOrderBy();
+                if (orderBy!=null&&orderBy.getItems().size() > 0) {
+                    println();
+                    print("ORDER BY ");
+                    printAndAccept(orderBy.getItems(), ", ");
+                    ((SQLSelect) parent).setOrderBy(null);
+                }
+            }
             println();
             print("FETCH FIRST ");
             x.getFirst().accept(this);
             print(" ROWS ONLY");
-        }
 
+
+        }
         if (x.isForReadOnly()) {
             println();
             print("FOR READ ONLY");
@@ -57,6 +74,7 @@ public class DB2OutputVisitor extends SQLASTOutputVisitor implements DB2ASTVisit
         return false;
     }
 
+
     @Override
     public void endVisit(DB2SelectQueryBlock x) {
 

src/test/java/com/alibaba/druid/bvt/sql/PagerUtilsTest_Limit_db2_0.java

@@ -50,4 +50,15 @@ public class PagerUtilsTest_Limit_db2_0 extends TestCase {
                             + "\nWHERE ROWNUM > 20"//
                             + "\n\tAND ROWNUM <= 30", result);
     }
+
+    public void test_fetch_order() {
+        String  sql="SELECT t.CUSTNAME AS custname\n" +
+                "FROM CPS_LOAN_INFO t WHERE t.DEL_FLAG = 0\n" +
+                "ORDER BY t.CREATE_TIME DESC";
+
+        String limitSql=PagerUtils.limit(sql, JdbcConstants.DB2,0,20)  ;
+        int fetchRowIndex=limitSql.indexOf("FETCH FIRST");
+        int orderIndex=limitSql.indexOf("ORDER BY") ;
+        Assert.assertTrue(fetchRowIndex>orderIndex);
+    }
 }