diff --git a/session_convert.go b/session_convert.go
index caff5d262..f43e12e07 100644
--- a/session_convert.go
+++ b/session_convert.go
@@ -554,6 +554,9 @@ func (session *Session) value2Interface(col *core.Column, fieldValue reflect.Val
 		if col.SQLType.IsBlob() {
 			return data, nil
 		}
+		if nil==data {
+			return nil,nil
+		}		
 		return string(data), nil
 	}
 
diff --git a/statement.go b/statement.go
index 585378a8b..f2ece73dd 100644
--- a/statement.go
+++ b/statement.go
@@ -318,7 +318,11 @@ func (statement *Statement) buildUpdates(bean interface{},
 			if err != nil {
 				engine.logger.Error(err)
 			} else {
-				val = data
+				if nil==data {
+					val=nil
+				}else{
+					val = data
+				}
 			}
 			goto APPEND
 		}