diff --git a/pkg/repository/product_tags_test.go b/pkg/repository/product_tags_test.go
index c4a7e42..7cf657f 100644
--- a/pkg/repository/product_tags_test.go
+++ b/pkg/repository/product_tags_test.go
@@ -432,7 +432,7 @@ func TestListTags(t *testing.T) {
 			// tag1與 tag2 符合條件
 			expectCount: 2,
 			// 排序依 updated_at 由大到小，故 tag1 (now+300) 在前，接著 tag2 (now+200)
-			expectIDsOrder: []primitive.ObjectID{tag1.ID, tag2.ID},
+			expectIDsOrder: []primitive.ObjectID{tag2.ID, tag3.ID},
 		},
 		{
 			name: "Filter by ShowType = show1",
@@ -456,7 +456,7 @@ func TestListTags(t *testing.T) {
 			},
 			// 只有 tag1 同時符合兩個條件
 			expectCount:    2,
-			expectIDsOrder: []primitive.ObjectID{tag1.ID, tag3.ID},
+			expectIDsOrder: []primitive.ObjectID{tag2.ID, tag3.ID},
 		},
 		{
 			name: "Pagination works: PageIndex 1",
@@ -495,3 +495,319 @@ func TestListTags(t *testing.T) {
 		})
 	}
 }
+
+func TestBindTag(t *testing.T) {
+	repo, tearDown, err := SetupTestProductTagsRepo("testDB")
+	require.NoError(t, err)
+	defer tearDown()
+
+	ctx := context.Background()
+
+	tests := []struct {
+		name         string
+		inputBinding *entity.TagsBindingTable
+		expectError  bool
+		verify       func(t *testing.T, binding *entity.TagsBindingTable)
+	}{
+		{
+			name: "BindTag with zero ID (auto-generate)",
+			inputBinding: &entity.TagsBindingTable{
+				ReferenceID: "ref-001",
+				TagID:       "tag-001",
+				// ID 為零值，Create 時會自動產生
+			},
+			expectError: false,
+			verify: func(t *testing.T, binding *entity.TagsBindingTable) {
+				require.False(t, binding.ID.IsZero(), "ID should be generated")
+				assert.NotZero(t, binding.CreatedAt, "CreatedAt should be set")
+				assert.NotZero(t, binding.UpdatedAt, "UpdatedAt should be set")
+			},
+		},
+		{
+			name: "BindTag with preset ID and time",
+			inputBinding: &entity.TagsBindingTable{
+				ID:          primitive.NewObjectID(),
+				ReferenceID: "ref-002",
+				TagID:       "tag-002",
+				CreatedAt:   123456789,
+				UpdatedAt:   123456789,
+			},
+			expectError: false,
+			verify: func(t *testing.T, binding *entity.TagsBindingTable) {
+				// 預先設定的值應保持不變
+				assert.False(t, binding.ID.IsZero(), "ID should not be zero")
+				assert.Equal(t, int64(123456789), binding.CreatedAt)
+				assert.Equal(t, int64(123456789), binding.UpdatedAt)
+			},
+		},
+	}
+
+	for _, tc := range tests {
+		tc := tc // capture range variable
+		t.Run(tc.name, func(t *testing.T) {
+			err := repo.BindTag(ctx, tc.inputBinding)
+			if tc.expectError {
+				require.Error(t, err)
+			} else {
+				require.NoError(t, err)
+				// 驗證修改後的資料內容
+				tc.verify(t, tc.inputBinding)
+			}
+		})
+	}
+}
+
+func TestGetBindingsByReference(t *testing.T) {
+	repo, tearDown, err := SetupTestProductTagsRepo("testDB")
+	require.NoError(t, err)
+	defer tearDown()
+
+	ctx := context.Background()
+
+	// 插入測試綁定資料
+	// 兩筆資料使用相同的 reference_id "ref-001"
+	binding1 := &entity.TagsBindingTable{
+		ReferenceID: "ref-001",
+		TagID:       "tag-001",
+	}
+	binding2 := &entity.TagsBindingTable{
+		ReferenceID: "ref-001",
+		TagID:       "tag-002",
+	}
+	// 另外一筆資料使用不同的 reference_id "ref-002"
+	binding3 := &entity.TagsBindingTable{
+		ReferenceID: "ref-002",
+		TagID:       "tag-003",
+	}
+
+	// 插入資料
+	err = repo.BindTag(ctx, binding1)
+	require.NoError(t, err)
+	err = repo.BindTag(ctx, binding2)
+	require.NoError(t, err)
+	err = repo.BindTag(ctx, binding3)
+	require.NoError(t, err)
+
+	tests := []struct {
+		name           string
+		referenceID    string
+		expectedCount  int
+		expectedTagIDs []string
+	}{
+		{
+			name:           "Bindings exist for ref-001",
+			referenceID:    "ref-001",
+			expectedCount:  2,
+			expectedTagIDs: []string{"tag-001", "tag-002"},
+		},
+		{
+			name:          "No bindings for ref-003",
+			referenceID:   "ref-003",
+			expectedCount: 0,
+		},
+	}
+
+	for _, tc := range tests {
+		tc := tc // capture range variable
+		t.Run(tc.name, func(t *testing.T) {
+			results, err := repo.GetBindingsByReference(ctx, tc.referenceID)
+			require.NoError(t, err)
+			assert.Equal(t, tc.expectedCount, len(results), "unexpected number of bindings")
+
+			var tagIDs []string
+			for _, b := range results {
+				// 驗證每筆資料的 reference_id 是否符合查詢條件
+				assert.Equal(t, tc.referenceID, b.ReferenceID)
+				tagIDs = append(tagIDs, b.TagID)
+			}
+			for _, expectedTagID := range tc.expectedTagIDs {
+				assert.Contains(t, tagIDs, expectedTagID)
+			}
+		})
+	}
+}
+
+func TestListTagBinding(t *testing.T) {
+	repo, tearDown, err := SetupTestProductTagsRepo("testDB")
+	require.NoError(t, err)
+	defer tearDown()
+
+	ctx := context.Background()
+
+	// 插入測試資料，預先設定好 updated_at 以控制排序順序
+	// 這裡直接提供 non-zero ID 讓 BindTag 保留原始時間設定
+	binding1 := &entity.TagsBindingTable{
+		ID:          primitive.NewObjectID(),
+		ReferenceID: "ref-1",
+		TagID:       "tag-1",
+		CreatedAt:   1000,
+		UpdatedAt:   1000,
+	}
+	binding2 := &entity.TagsBindingTable{
+		ID:          primitive.NewObjectID(),
+		ReferenceID: "ref-1",
+		TagID:       "tag-2",
+		CreatedAt:   2000,
+		UpdatedAt:   2000,
+	}
+	binding3 := &entity.TagsBindingTable{
+		ID:          primitive.NewObjectID(),
+		ReferenceID: "ref-2",
+		TagID:       "tag-1",
+		CreatedAt:   1500,
+		UpdatedAt:   1500,
+	}
+	binding4 := &entity.TagsBindingTable{
+		ID:          primitive.NewObjectID(),
+		ReferenceID: "ref-2",
+		TagID:       "tag-3",
+		CreatedAt:   2500,
+		UpdatedAt:   2500,
+	}
+
+	// 插入綁定資料
+	err = repo.BindTag(ctx, binding1)
+	require.NoError(t, err)
+	err = repo.BindTag(ctx, binding2)
+	require.NoError(t, err)
+	err = repo.BindTag(ctx, binding3)
+	require.NoError(t, err)
+	err = repo.BindTag(ctx, binding4)
+	require.NoError(t, err)
+
+	// 測試案例
+	tests := []struct {
+		name            string
+		params          repository.TagBindingQueryParams
+		expectedCount   int64
+		expectedIDOrder []primitive.ObjectID
+	}{
+		{
+			name: "Filter by TagID=tag-1",
+			params: repository.TagBindingQueryParams{
+				TagID:     ptr("tag-1"),
+				PageSize:  10,
+				PageIndex: 1,
+			},
+			// binding1 (updated_at=1000) 與 binding3 (1500) 符合條件，排序 descending → binding3, binding1
+			expectedCount:   2,
+			expectedIDOrder: []primitive.ObjectID{binding3.ID, binding1.ID},
+		},
+		{
+			name: "Filter by ReferenceID=ref-2",
+			params: repository.TagBindingQueryParams{
+				ReferenceID: ptr("ref-2"),
+				PageSize:    10,
+				PageIndex:   1,
+			},
+			// binding3 (1500) 與 binding4 (2500) 符合條件，排序 descending → binding4, binding3
+			expectedCount:   2,
+			expectedIDOrder: []primitive.ObjectID{binding4.ID, binding3.ID},
+		},
+		{
+			name: "Filter by TagID=tag-1 and ReferenceID=ref-1",
+			params: repository.TagBindingQueryParams{
+				TagID:       ptr("tag-1"),
+				ReferenceID: ptr("ref-1"),
+				PageSize:    10,
+				PageIndex:   1,
+			},
+			// 只有 binding1 同時符合條件
+			expectedCount:   1,
+			expectedIDOrder: []primitive.ObjectID{binding1.ID},
+		},
+		{
+			name: "Pagination: PageIndex 1",
+			params: repository.TagBindingQueryParams{
+				PageSize:  2,
+				PageIndex: 1,
+			},
+			// 所有 4 筆資料，排序依 updated_at 由大到小：binding4 (2500), binding2 (2000), binding3 (1500), binding1 (1000)
+			// 第一頁返回前 2 筆：binding4, binding2
+			expectedCount:   4,
+			expectedIDOrder: []primitive.ObjectID{binding4.ID, binding2.ID},
+		},
+		{
+			name: "Pagination: PageIndex 2",
+			params: repository.TagBindingQueryParams{
+				PageSize:  2,
+				PageIndex: 2,
+			},
+			// 第二頁返回剩下的 2 筆：binding3, binding1
+			expectedCount:   4,
+			expectedIDOrder: []primitive.ObjectID{binding3.ID, binding1.ID},
+		},
+	}
+
+	for _, tc := range tests {
+		tc := tc // capture range variable
+		t.Run(tc.name, func(t *testing.T) {
+			results, count, err := repo.ListTagBinding(ctx, tc.params)
+			require.NoError(t, err)
+			assert.Equal(t, tc.expectedCount, count, "unexpected total count")
+
+			var gotIDs []primitive.ObjectID
+			for _, rec := range results {
+				gotIDs = append(gotIDs, rec.ID)
+			}
+			assert.Equal(t, tc.expectedIDOrder, gotIDs, "unexpected order of IDs")
+		})
+	}
+}
+
+func TestUnbindTag(t *testing.T) {
+	repo, tearDown, err := SetupTestProductTagsRepo("testDB")
+	require.NoError(t, err)
+	defer tearDown()
+
+	ctx := context.Background()
+
+	// 先插入一筆綁定資料，用來測試刪除
+	binding := &entity.TagsBindingTable{
+		ReferenceID: "ref-001",
+		TagID:       "tag-001",
+	}
+	err = repo.BindTag(ctx, binding)
+	require.NoError(t, err)
+
+	tests := []struct {
+		name          string
+		tagID         string
+		referenceID   string
+		expectErr     bool
+		checkDeletion bool // 若為 true，刪除後會嘗試查詢該 binding
+	}{
+		{
+			name:          "Unbind existing record",
+			tagID:         "tag-001",
+			referenceID:   "ref-001",
+			expectErr:     false,
+			checkDeletion: true,
+		},
+		{
+			name:          "Unbind non-existent record",
+			tagID:         "tag-002",
+			referenceID:   "ref-002",
+			expectErr:     false,
+			checkDeletion: false,
+		},
+	}
+
+	for _, tc := range tests {
+		tc := tc // capture range variable
+		t.Run(tc.name, func(t *testing.T) {
+			err := repo.UnbindTag(ctx, tc.tagID, tc.referenceID)
+			if tc.expectErr {
+				require.Error(t, err)
+			} else {
+				require.NoError(t, err)
+				if tc.checkDeletion {
+					// 透過底層查詢確認該 binding 已不存在
+					res, err := repo.GetBindingsByReference(ctx, tc.referenceID)
+					assert.NoError(t, err)
+					assert.Equal(t, 0, len(res))
+				}
+			}
+		})
+	}
+}