diff --git a/convert.go b/convert.go
deleted file mode 100644
index 371ec2bc..00000000
--- a/convert.go
+++ /dev/null
@@ -1,49 +0,0 @@
-// Copyright 2017 The Xorm Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package xorm
-
-import (
-	"fmt"
-	"reflect"
-	"strconv"
-)
-
-func asKind(vv reflect.Value, tp reflect.Type) (interface{}, error) {
-	switch tp.Kind() {
-	case reflect.Ptr:
-		return asKind(vv.Elem(), tp.Elem())
-	case reflect.Int64:
-		return vv.Int(), nil
-	case reflect.Int:
-		return int(vv.Int()), nil
-	case reflect.Int32:
-		return int32(vv.Int()), nil
-	case reflect.Int16:
-		return int16(vv.Int()), nil
-	case reflect.Int8:
-		return int8(vv.Int()), nil
-	case reflect.Uint64:
-		return vv.Uint(), nil
-	case reflect.Uint:
-		return uint(vv.Uint()), nil
-	case reflect.Uint32:
-		return uint32(vv.Uint()), nil
-	case reflect.Uint16:
-		return uint16(vv.Uint()), nil
-	case reflect.Uint8:
-		return uint8(vv.Uint()), nil
-	case reflect.String:
-		return vv.String(), nil
-	case reflect.Slice:
-		if tp.Elem().Kind() == reflect.Uint8 {
-			v, err := strconv.ParseInt(string(vv.Interface().([]byte)), 10, 64)
-			if err != nil {
-				return nil, err
-			}
-			return v, nil
-		}
-	}
-	return nil, fmt.Errorf("unsupported primary key type: %v, %v", tp, vv)
-}