diff --git a/models/class_board.go b/models/class_board.go
index 068f1c1..83ed439 100644
--- a/models/class_board.go
+++ b/models/class_board.go
@@ -10,7 +10,7 @@ type ClassBoard struct {
 	CreatedAt   time.Time `gorm:"not null;"`
 	UpdatedAt   time.Time `gorm:"not null;"`
 	IsAnnounced bool      `gorm:"not null;default:false"`
-	CID         uint      `gorm:"column:cid;not null;constraint:OnUpdate:CASCADE,OnDelete:SET NULL;"`
+	CID         uint      `gorm:"column:cid;not null;constraint:OnUpdate:CASCADE,OnDelete:CASCADE;"`
 	UID         uint      `gorm:"column:uid;not null"` // User ID
 	Class       Class     `gorm:"foreignKey:CID;constraint:OnDelete:CASCADE"`
 	User        User      `gorm:"foreignKey:UID"`
diff --git a/models/class_code.go b/models/class_code.go
index 123883b..27ab4e3 100644
--- a/models/class_code.go
+++ b/models/class_code.go
@@ -4,7 +4,7 @@ type ClassCode struct {
 	ID     uint    `gorm:"primaryKey;size:255;autoIncrement"`
 	Code   string  `gorm:"size:10;not null"`
 	Secret *string `gorm:"size:20"`
-	CID    uint    `gorm:"column:cid;not null;constraint:OnUpdate:CASCADE,OnDelete:SET NULL;"`
+	CID    uint    `gorm:"column:cid;not null;constraint:OnUpdate:CASCADE,OnDelete:CASCADE;"`
 	UID    uint    `gorm:"column:uid;not null"` // User ID
 	Class  Class   `gorm:"foreignKey:CID;constraint:OnDelete:CASCADE"`
 	User   User    `gorm:"foreignKey:UID"`
diff --git a/repositories/class_user_repository.go b/repositories/class_user_repository.go
index 47ee768..1477d13 100644
--- a/repositories/class_user_repository.go
+++ b/repositories/class_user_repository.go
@@ -220,10 +220,16 @@ func (r *classUserRepository) RoleExists(uid uint, cid uint) (bool, error) {
 }
 
 func (r *classUserRepository) CreateUserRole(uid uint, cid uint, role string) error {
+	var user models.User
+	if err := r.db.First(&user, uid).Error; err != nil {
+		return err
+	}
+
 	newUserRole := models.ClassUser{
-		UID:  uid,
-		CID:  cid,
-		Role: role,
+		UID:      uid,
+		CID:      cid,
+		Role:     role,
+		Nickname: user.Name,
 	}
 	return r.db.Create(&newUserRole).Error
 }