diff --git a/backend/src/main/java/com/qqchen/deploy/backend/entity/User.java b/backend/src/main/java/com/qqchen/deploy/backend/entity/User.java
index 3ae3b4b1..c98f00f1 100644
--- a/backend/src/main/java/com/qqchen/deploy/backend/entity/User.java
+++ b/backend/src/main/java/com/qqchen/deploy/backend/entity/User.java
@@ -48,7 +48,7 @@ public class User extends Entity<Long> {
 
 
     @OneToMany(mappedBy = "user", cascade = CascadeType.ALL) // 指向 UserRole 的 user 属性
-    private List<UserRole> userRoles;
+    private Set<UserRole> userRoles;
 
 //    public void addRole(Role role) {
 //        UserRole userRole = new UserRole(this, role);
diff --git a/backend/src/main/java/com/qqchen/deploy/backend/repository/UserRoleRepository.java b/backend/src/main/java/com/qqchen/deploy/backend/repository/UserRoleRepository.java
index 5919bd72..b85324a7 100644
--- a/backend/src/main/java/com/qqchen/deploy/backend/repository/UserRoleRepository.java
+++ b/backend/src/main/java/com/qqchen/deploy/backend/repository/UserRoleRepository.java
@@ -3,16 +3,25 @@ package com.qqchen.deploy.backend.repository;
 
 import com.qqchen.deploy.backend.common.repository.BaseRepository;
 import com.qqchen.deploy.backend.entity.UserRole;
+import org.springframework.data.jpa.repository.Modifying;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.query.Param;
 import org.springframework.stereotype.Repository;
 
-import java.util.List;
+import java.util.Set;
 
 @Repository
 public interface UserRoleRepository extends BaseRepository<UserRole, Long> {
-    
-    List<UserRole> findByUserId(Long userId);
-    
-    void deleteByUserId(Long userId);
-    
-    List<UserRole> findByRoleId(Long roleId);
+
+    @Query("SELECT ur FROM UserRole ur WHERE ur.user.id = :userId")
+    Set<UserRole> findByUserId(@Param("userId") Long userId);
+
+    @Modifying
+    @Query("DELETE FROM UserRole ur WHERE ur.user.id = :userId AND ur.role.id = :roleId")
+    void deleteByUserIdAndRoleId(@Param("userId") Long userId, @Param("roleId") Long roleId);
+
+
+    @Query("SELECT COUNT(ur) > 0 FROM UserRole ur WHERE ur.user.id = :userId AND ur.role.id = :roleId")
+    boolean existsByUserIdAndRoleId(@Param("userId") Long userId, @Param("roleId") Long roleId);
+
 } 
\ No newline at end of file