Check for existence of connection before trying to close it

git-svn-id: https://svn.apache.org/repos/asf/db/ddlutils/trunk@572520 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/src/java/org/apache/ddlutils/io/DataToDatabaseSink.java b/src/java/org/apache/ddlutils/io/DataToDatabaseSink.java
index 1f8ef96..bde5a1e 100644
--- a/src/java/org/apache/ddlutils/io/DataToDatabaseSink.java
+++ b/src/java/org/apache/ddlutils/io/DataToDatabaseSink.java
@@ -210,13 +210,16 @@
     public void end() throws DataSinkException

     {

         purgeBatchQueue();

-        try

+        if (_connection != null)

         {

-            _connection.close();

-        }

-        catch (SQLException ex)

-        {

-            throw new DataSinkException(ex);

+            try

+            {

+                _connection.close();

+            }

+            catch (SQLException ex)

+            {

+                throw new DataSinkException(ex);

+            }

         }

         if (!_waitingObjects.isEmpty())

         {