diff --git a/.idea/vcs.xml b/.idea/vcs.xml
new file mode 100644
index 00000000..94a25f7f
--- /dev/null
+++ b/.idea/vcs.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="VcsDirectoryMappings">
+    <mapping directory="$PROJECT_DIR$" vcs="Git" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/callback_create.go b/callback_create.go
index a4da39e8..76d62a31 100644
--- a/callback_create.go
+++ b/callback_create.go
@@ -3,6 +3,7 @@ package gorm
 import (
 	"fmt"
 	"strings"
+	"reflect"
 )
 
 // Define callbacks for creating
@@ -35,13 +36,33 @@ func updateTimeStampForCreateCallback(scope *Scope) {
 
 		if createdAtField, ok := scope.FieldByName("CreatedAt"); ok {
 			if createdAtField.IsBlank {
-				createdAtField.Set(now)
+				switch createdAtField.Field.Type().Kind() {
+				case reflect.Int64:
+					createdAtField.Set(now.Unix())
+					break
+				case reflect.String:
+					createdAtField.Set(now.String())
+					break
+				default:
+					createdAtField.Set(now)
+					break
+				}
 			}
 		}
 
 		if updatedAtField, ok := scope.FieldByName("UpdatedAt"); ok {
 			if updatedAtField.IsBlank {
-				updatedAtField.Set(now)
+				switch updatedAtField.Field.Type().Kind() {
+				case reflect.Int64:
+					updatedAtField.Set(now.Unix())
+					break
+				case reflect.String:
+					updatedAtField.Set(now.String())
+					break
+				default:
+					updatedAtField.Set(now)
+					break
+				}
 			}
 		}
 	}
diff --git a/callback_delete.go b/callback_delete.go
index 73d90880..f732f4dd 100644
--- a/callback_delete.go
+++ b/callback_delete.go
@@ -3,6 +3,7 @@ package gorm
 import (
 	"errors"
 	"fmt"
+	"reflect"
 )
 
 // Define callbacks for deleting
@@ -36,11 +37,23 @@ func deleteCallback(scope *Scope) {
 		deletedAtField, hasDeletedAtField := scope.FieldByName("DeletedAt")
 
 		if !scope.Search.Unscoped && hasDeletedAtField {
+			var time interface{}
+			switch deletedAtField.Field.Type().Kind() {
+			case reflect.Int64:
+				time = NowFunc().Unix()
+				break
+			case reflect.String:
+				time = NowFunc().String()
+				break
+			default:
+				time = NowFunc()
+				break
+			}
 			scope.Raw(fmt.Sprintf(
 				"UPDATE %v SET %v=%v%v%v",
 				scope.QuotedTableName(),
 				scope.Quote(deletedAtField.DBName),
-				scope.AddToVars(NowFunc()),
+				scope.AddToVars(time),
 				addExtraSpaceIfExist(scope.CombinedConditionSql()),
 				addExtraSpaceIfExist(extraOption),
 			)).Exec()
diff --git a/callback_update.go b/callback_update.go
index 6948439f..d4ef773b 100644
--- a/callback_update.go
+++ b/callback_update.go
@@ -4,6 +4,7 @@ import (
 	"errors"
 	"fmt"
 	"strings"
+	"reflect"
 )
 
 // Define callbacks for updating
@@ -48,8 +49,22 @@ func beforeUpdateCallback(scope *Scope) {
 
 // updateTimeStampForUpdateCallback will set `UpdatedAt` when updating
 func updateTimeStampForUpdateCallback(scope *Scope) {
+	var time interface{}
+	if createdAtField, ok := scope.FieldByName("UpdatedAt"); ok {
+		switch createdAtField.Field.Type().Kind() {
+		case reflect.Int64:
+			time = NowFunc().Unix()
+			break
+		case reflect.String:
+			time = NowFunc().String()
+			break
+		default:
+			time = NowFunc()
+			break
+		}
+	}
 	if _, ok := scope.Get("gorm:update_column"); !ok {
-		scope.SetColumn("UpdatedAt", NowFunc())
+		scope.SetColumn("UpdatedAt", time)
 	}
 }
 
diff --git a/model.go b/model.go
index f37ff7ea..5e4c284a 100644
--- a/model.go
+++ b/model.go
@@ -12,3 +12,17 @@ type Model struct {
 	UpdatedAt time.Time
 	DeletedAt *time.Time `sql:"index"`
 }
+
+type ModelInt64 struct {
+	ID        uint `gorm:"primary_key"`
+	UpdatedAt int64
+	CreatedAt int64
+	DeletedAt int64 `sql:"index"`
+}
+
+type ModelString struct {
+	ID        uint `gorm:"primary_key"`
+	UpdatedAt string
+	CreatedAt string
+	DeletedAt string `sql:"index"`
+}
diff --git a/scope.go b/scope.go
index fda7f653..fba35b1d 100644
--- a/scope.go
+++ b/scope.go
@@ -687,8 +687,19 @@ func (scope *Scope) whereSQL() (sql string) {
 		primaryConditions, andConditions, orConditions []string
 	)
 
+	switch deletedAtField.Field.Type().Kind() {
+	case reflect.Int64:
+		sql = fmt.Sprintf("%v.%v = 0", quotedTableName, scope.Quote(deletedAtField.DBName))
+		break
+	case reflect.String:
+		sql = fmt.Sprintf("%v.%v = ''", quotedTableName, scope.Quote(deletedAtField.DBName))
+		break
+	default:
+		sql = fmt.Sprintf("%v.%v IS NULL", quotedTableName, scope.Quote(deletedAtField.DBName))
+		break
+	}
+
 	if !scope.Search.Unscoped && hasDeletedAtField {
-		sql := fmt.Sprintf("%v.%v IS NULL", quotedTableName, scope.Quote(deletedAtField.DBName))
 		primaryConditions = append(primaryConditions, sql)
 	}