diff --git a/src/main/java/com/alibaba/druid/pool/vendor/MySqlValidConnectionChecker.java b/src/main/java/com/alibaba/druid/pool/vendor/MySqlValidConnectionChecker.java
index 97aaf38d68..9278799d55 100644
--- a/src/main/java/com/alibaba/druid/pool/vendor/MySqlValidConnectionChecker.java
+++ b/src/main/java/com/alibaba/druid/pool/vendor/MySqlValidConnectionChecker.java
@@ -105,7 +105,7 @@ public class MySqlValidConnectionChecker extends ValidConnectionCheckerAdapter i
             }
         }
 
-        if (validateQuery == null) {
+        if (validateQuery == null || validateQuery.length() == 0) {
             return true;
         }
 
diff --git a/src/main/java/com/alibaba/druid/pool/vendor/OracleValidConnectionChecker.java b/src/main/java/com/alibaba/druid/pool/vendor/OracleValidConnectionChecker.java
index 383869bfec..db54c93da3 100644
--- a/src/main/java/com/alibaba/druid/pool/vendor/OracleValidConnectionChecker.java
+++ b/src/main/java/com/alibaba/druid/pool/vendor/OracleValidConnectionChecker.java
@@ -70,6 +70,10 @@ public class OracleValidConnectionChecker extends ValidConnectionCheckerAdapter
             conn = ((ConnectionProxy) conn).getRawObject();
         }
 
+        if (validateQuery == null || validateQuery.length() == 0) {
+            return true;
+        }
+
         Statement stmt = null;
         ResultSet rs = null;
         try {