bug fixed for PagerUtils, for issue alibaba#3081

src/main/java/com/alibaba/druid/sql/PagerUtils.java

@@ -272,8 +272,13 @@ private static boolean limitSQLServer(SQLSelect select, String dbType, int offse
 
             SQLAggregateExpr aggregateExpr = new SQLAggregateExpr("ROW_NUMBER");
             SQLOrderBy orderBy = select.getOrderBy();
-            aggregateExpr.setOver(new SQLOver(orderBy));
-            select.setOrderBy(null);
+            if (orderBy != null) {
+                aggregateExpr.setOver(new SQLOver(orderBy));
+                select.setOrderBy(null);
+            } else if (queryBlock.getOrderBy() != null){
+                aggregateExpr.setOver(new SQLOver(queryBlock.getOrderBy()));
+                queryBlock.setOrderBy(null);
+            }
 
             queryBlock.getSelectList().add(new SQLSelectItem(aggregateExpr, "ROWNUM"));
 

src/test/java/com/alibaba/druid/bvt/sql/PagerUtilsTest_Limit_SQLServer_6.java

@@ -0,0 +1,21 @@
+package com.alibaba.druid.bvt.sql;
+
+import com.alibaba.druid.sql.PagerUtils;
+import com.alibaba.druid.util.JdbcConstants;
+import junit.framework.TestCase;
+import org.junit.Assert;
+
+public class PagerUtilsTest_Limit_SQLServer_6 extends TestCase {
+
+    public void test_db2_union() throws Exception {
+        String sql = "SELECT t.name USER_NAME, t.xxx FROM t_sd_users t ORDER BY t.name ASC";
+        String result = PagerUtils.limit(sql, JdbcConstants.SQL_SERVER, 10, 10);
+        Assert.assertEquals("SELECT *\n" +
+                "FROM (\n" +
+                "\tSELECT t.name AS USER_NAME, t.xxx, ROW_NUMBER() OVER (ORDER BY t.name ASC) AS ROWNUM\n" +
+                "\tFROM t_sd_users t\n" +
+                ") XX\n" +
+                "WHERE ROWNUM > 10\n" +
+                "\tAND ROWNUM <= 20", result);
+    }
+}