diff --git a/model/user.go b/model/user.go
index 7b25c61b..021810c0 100644
--- a/model/user.go
+++ b/model/user.go
@@ -49,7 +49,7 @@ type User struct {
 	UsedQuota        int64  `json:"used_quota" gorm:"bigint;default:0;column:used_quota"` // used quota
 	RequestCount     int    `json:"request_count" gorm:"type:int;default:0;"`             // request number
 	Group            string `json:"group" gorm:"type:varchar(32);default:'default'"`
-	AffCode          string `json:"aff_code" gorm:"type:varchar(32);column:aff_code"`
+	AffCode          string `json:"aff_code" gorm:"type:varchar(32);column:aff_code;uniqueIndex"`
 	InviterId        int    `json:"inviter_id" gorm:"type:int;column:inviter_id;index"`
 }