fix

fine-druid/src/com/fr/third/alibaba/druid/pool/vendor/MSSQLValidConnectionChecker.java

@@ -28,20 +28,25 @@ import com.fr.third.alibaba.druid.util.JdbcUtils;
  * A MSSQLValidConnectionChecker.
  */
 public class MSSQLValidConnectionChecker extends ValidConnectionCheckerAdapter implements ValidConnectionChecker, Serializable {
-
+    
     private static final long serialVersionUID = 1L;
-
-    public MSSQLValidConnectionChecker(){
-
+    
+    public MSSQLValidConnectionChecker() {
+    
     }
-
+    
     public boolean isValidConnection(final Connection c, String validateQuery, int validationQueryTimeout) throws Exception {
+        
         if (c.isClosed()) {
             return false;
         }
-
+        
+        if (validateQuery == null || validateQuery.isEmpty()) {
+            validateQuery = "select 1";
+        }
+        
         Statement stmt = null;
-
+        
         try {
             stmt = c.createStatement();
             if (validationQueryTimeout > 0) {
@@ -55,5 +60,5 @@ public class MSSQLValidConnectionChecker extends ValidConnectionCheckerAdapter i
             JdbcUtils.close(stmt);
         }
     }
-
-}
+    
+}