improve DB2ExceptionSorter

src/main/java/com/alibaba/druid/pool/vendor/DB2ExceptionSorter.java

@@ -24,9 +24,22 @@ public class DB2ExceptionSorter implements ExceptionSorter {
 
     @Override
     public boolean isExceptionFatal(SQLException e) {
+        String sqlState = e.getSQLState();
+        if (sqlState != null && sqlState.startsWith("08")) { // Connection Exception
+            return true;
+        }
+
         int errorCode = e.getErrorCode();
-        switch (errorCode) { // THE CURSOR IS NOT IN A PREPARED STATE
-            case -514:
+        switch (errorCode) {
+            case -512: // STATEMENT REFERENCE TO REMOTE OBJECT IS INVALID
+            case -514: // THE CURSOR IS NOT IN A PREPARED STATE
+            case -516: // THE DESCRIBE STATEMENT DOES NOT SPECIFY A PREPARED STATEMENT
+            case -518: // THE EXECUTE STATEMENT DOES NOT IDENTIFY A VALID PREPARED STATEMENT
+            case -525: // THE SQL STATEMENT CANNOT BE EXECUTED BECAUSE IT WAS IN ERROR AT BIND TIME FOR SECTION = sectno
+                       // PACKAGE = pkgname CONSISTENCY TOKEN = contoken
+            case -909: // THE OBJECT HAS BEEN DELETED OR ALTERED
+            case -918: // THE SQL STATEMENT CANNOT BE EXECUTED BECAUSE A CONNECTION HAS BEEN LOST
+            case -924: // DB2 CONNECTION INTERNAL ERROR, function-code,return-code,reason-code
                 return true;
             default:
                 break;