diff --git a/association.go b/association.go
index 4bc7269f..1d3777f5 100644
--- a/association.go
+++ b/association.go
@@ -82,85 +82,65 @@ func (association *Association) Append(values ...interface{}) *Association {
 }
 
 func (association *Association) Replace(values ...interface{}) *Association {
-	relationship := association.Field.Relationship
-	scope := association.Scope
-	field := association.Field.Field
+	var (
+		relationship = association.Field.Relationship
+		scope        = association.Scope
+		field        = association.Field.Field
+		newDB        = scope.NewDB()
+	)
 
-	// get old primary keys
-	oldPrimaryKeys := association.getPrimaryKeys(relationship.AssociationForeignFieldNames, field.Interface())
-
-	// append new values
+	// Append new values
 	association.Field.Set(reflect.Zero(association.Field.Field.Type()))
 	association.Append(values...)
 
-	// get new primary keys
-	var newPrimaryKeys [][]interface{}
-	if len(values) > 0 {
-		newPrimaryKeys = association.getPrimaryKeys(relationship.AssociationForeignFieldNames, field.Interface())
-	}
-
-	var addedPrimaryKeys = [][]interface{}{}
-	for _, newKey := range newPrimaryKeys {
-		hasEqual := false
-		for _, oldKey := range oldPrimaryKeys {
-			if equalAsString(newKey, oldKey) {
-				hasEqual = true
-				break
-			}
-		}
-		if !hasEqual {
-			addedPrimaryKeys = append(addedPrimaryKeys, newKey)
-		}
-	}
-
-	for _, primaryKey := range association.getPrimaryKeys(relationship.AssociationForeignFieldNames, values...) {
-		addedPrimaryKeys = append(addedPrimaryKeys, primaryKey)
-	}
-
-	query := scope.NewDB()
-	var foreignKeyMap = map[string]interface{}{}
-
+	// Belongs To
 	if relationship.Kind == "belongs_to" {
-		for idx, foreignKey := range relationship.AssociationForeignDBNames {
-			if field, ok := scope.FieldByName(relationship.AssociationForeignFieldNames[idx]); ok {
-				query = query.Where(fmt.Sprintf("%v = ?", scope.Quote(foreignKey)), field.Field.Interface())
+		// Set foreign key to be null only when clearing value
+		if len(values) == 0 {
+			// Set foreign key to be nil
+			var foreignKeyMap = map[string]interface{}{}
+			for _, foreignKey := range relationship.ForeignDBNames {
+				foreignKeyMap[foreignKey] = nil
 			}
+			association.setErr(newDB.Model(scope.Value).UpdateColumn(foreignKeyMap).Error)
 		}
-
-		for _, foreignKey := range relationship.ForeignDBNames {
-			foreignKeyMap[foreignKey] = nil
-		}
-
-		if len(addedPrimaryKeys) > 0 {
-			sql := fmt.Sprintf("%v NOT IN (%v)", toQueryCondition(scope, relationship.ForeignDBNames), toQueryMarks(addedPrimaryKeys))
-			query = query.Where(sql, toQueryValues(addedPrimaryKeys)...)
-		}
-
-		modelValue := scope.Value
-		// if replacing with a new value, don't reset current foreign key
-		// if clearing foreign value, then reset the foreign key to null
-		if len(values) > 0 {
-			modelValue = reflect.New(scope.GetModelStruct().ModelType).Interface()
-		}
-		association.setErr(query.Model(modelValue).UpdateColumn(foreignKeyMap).Error)
 	} else {
+		// Relations
+		var foreignKeyMap = map[string]interface{}{}
 		for idx, foreignKey := range relationship.ForeignDBNames {
 			foreignKeyMap[foreignKey] = nil
 			if field, ok := scope.FieldByName(relationship.AssociationForeignFieldNames[idx]); ok {
-				query = query.Where(fmt.Sprintf("%v = ?", scope.Quote(foreignKey)), field.Field.Interface())
+				newDB = newDB.Where(fmt.Sprintf("%v = ?", scope.Quote(foreignKey)), field.Field.Interface())
 			}
 		}
 
-		if len(addedPrimaryKeys) > 0 {
-			sql := fmt.Sprintf("%v NOT IN (%v)", toQueryCondition(scope, relationship.AssociationForeignDBNames), toQueryMarks(addedPrimaryKeys))
-			query = query.Where(sql, toQueryValues(addedPrimaryKeys)...)
+		// Relations except new created
+		if len(values) > 0 {
+			var newPrimaryKeys [][]interface{}
+			var associationForeignFieldNames []string
+
+			if relationship.Kind == "many2many" {
+				// If many to many relations, get it from foreign key
+				associationForeignFieldNames = relationship.AssociationForeignFieldNames
+			} else {
+				// If other relations, get real primary keys
+				for _, field := range scope.New(reflect.New(field.Type()).Interface()).Fields() {
+					if field.IsPrimaryKey {
+						associationForeignFieldNames = append(associationForeignFieldNames, field.Name)
+					}
+				}
+			}
+
+			newPrimaryKeys = association.getPrimaryKeys(associationForeignFieldNames, field.Interface())
+			sql := fmt.Sprintf("%v NOT IN (%v)", toQueryCondition(scope, relationship.AssociationForeignDBNames), toQueryMarks(newPrimaryKeys))
+			newDB = newDB.Where(sql, toQueryValues(newPrimaryKeys)...)
 		}
 
 		if relationship.Kind == "many_to_many" {
-			association.setErr(relationship.JoinTableHandler.Delete(relationship.JoinTableHandler, query, relationship))
+			association.setErr(relationship.JoinTableHandler.Delete(relationship.JoinTableHandler, newDB, relationship))
 		} else if relationship.Kind == "has_one" || relationship.Kind == "has_many" {
 			fieldValue := reflect.New(association.Field.Field.Type()).Interface()
-			association.setErr(query.Model(fieldValue).UpdateColumn(foreignKeyMap).Error)
+			association.setErr(newDB.Debug().Model(fieldValue).UpdateColumn(foreignKeyMap).Error)
 		}
 	}
 	return association
diff --git a/association_test.go b/association_test.go
index 92854d89..37ed1bb8 100644
--- a/association_test.go
+++ b/association_test.go
@@ -8,12 +8,9 @@ import (
 )
 
 func TestBelongsTo(t *testing.T) {
-	DB.DropTable(Category{}, Post{})
-	DB.CreateTable(Category{}, Post{})
-
 	post := Post{
-		Title:        "post 1",
-		Body:         "body 1",
+		Title:        "post belongs to",
+		Body:         "body belongs to",
 		Category:     Category{Name: "Category 1"},
 		MainCategory: Category{Name: "Main Category 1"},
 	}
@@ -34,19 +31,19 @@ func TestBelongsTo(t *testing.T) {
 	var category1 Category
 	DB.Model(&post).Association("Category").Find(&category1)
 	if category1.Name != "Category 1" {
-		t.Errorf("Query has one relations with Association")
+		t.Errorf("Query belongs to relations with Association")
 	}
 
 	var mainCategory1 Category
 	DB.Model(&post).Association("MainCategory").Find(&mainCategory1)
 	if mainCategory1.Name != "Main Category 1" {
-		t.Errorf("Query has one relations with Association")
+		t.Errorf("Query belongs to relations with Association")
 	}
 
 	var category11 Category
 	DB.Model(&post).Related(&category11)
 	if category11.Name != "Category 1" {
-		t.Errorf("Query has one relations with Related")
+		t.Errorf("Query belongs to relations with Related")
 	}
 
 	// Append
@@ -114,12 +111,9 @@ func TestBelongsTo(t *testing.T) {
 }
 
 func TestHasMany(t *testing.T) {
-	DB.DropTable(Post{}, Comment{})
-	DB.CreateTable(Post{}, Comment{})
-
 	post := Post{
-		Title:    "post 1",
-		Body:     "body 1",
+		Title:    "post has many",
+		Body:     "body has many",
 		Comments: []*Comment{{Content: "Comment 1"}, {Content: "Comment 2"}},
 	}
 
@@ -213,51 +207,69 @@ func TestHasMany(t *testing.T) {
 	}
 }
 
-func TestHasOneAndHasManyAssociation(t *testing.T) {
-	DB.DropTable(Category{}, Post{}, Comment{})
-	DB.CreateTable(Category{}, Post{}, Comment{})
-
-	post := Post{
-		Title:        "post 1",
-		Body:         "body 1",
-		Comments:     []*Comment{{Content: "Comment 1"}, {Content: "Comment 2"}},
-		Category:     Category{Name: "Category 1"},
-		MainCategory: Category{Name: "Main Category 1"},
+func TestHasOne(t *testing.T) {
+	user := User{
+		Name:       "has one",
+		CreditCard: CreditCard{Number: "411111111111"},
 	}
 
-	if err := DB.Save(&post).Error; err != nil {
-		t.Errorf("Got errors when save post", err.Error())
+	if err := DB.Save(&user).Error; err != nil {
+		t.Errorf("Got errors when save user", err.Error())
 	}
 
-	if err := DB.First(&Category{}, "name = ?", "Category 1").Error; err != nil {
-		t.Errorf("Category should be saved", err.Error())
+	if user.CreditCard.UserId.Int64 == 0 {
+		t.Errorf("CreditCard's foreign key should be updated")
 	}
 
-	var p Post
-	DB.First(&p, post.Id)
+	// Query
+	var creditCard1 CreditCard
+	DB.Model(&user).Related(&creditCard1)
 
-	if post.CategoryId.Int64 == 0 || p.CategoryId.Int64 == 0 || post.MainCategoryId == 0 || p.MainCategoryId == 0 {
-		t.Errorf("Category Id should exist")
+	if creditCard1.Number != "411111111111" {
+		t.Errorf("Query has one relations with Related")
 	}
 
-	if DB.First(&Comment{}, "content = ?", "Comment 1").Error != nil {
-		t.Errorf("Comment 1 should be saved")
-	}
-	if post.Comments[0].PostId == 0 {
-		t.Errorf("Comment Should have post id")
+	var creditCard11 CreditCard
+	DB.Model(&user).Association("CreditCard").Find(&creditCard11)
+
+	if creditCard11.Number != "411111111111" {
+		t.Errorf("Query has one relations with Related")
 	}
 
-	var comment Comment
-	if DB.First(&comment, "content = ?", "Comment 2").Error != nil {
-		t.Errorf("Comment 2 should be saved")
+	// Append
+	var creditcard2 = CreditCard{
+		Number: "411111111112",
+	}
+	DB.Model(&user).Association("CreditCard").Append(&creditcard2)
+
+	if creditcard2.ID == 0 {
+		t.Errorf("Creditcard should has ID when created with Append")
 	}
 
-	if comment.PostId == 0 {
-		t.Errorf("Comment 2 Should have post id")
+	var creditcard21 CreditCard
+	DB.Model(&user).Related(&creditcard21)
+	if creditcard21.Number != "411111111112" {
+		t.Errorf("CreditCard should be updated with Append")
 	}
 
-	comment3 := Comment{Content: "Comment 3", Post: Post{Title: "Title 3", Body: "Body 3"}}
-	DB.Save(&comment3)
+	// Replace
+	var creditcard3 = CreditCard{
+		Number: "411111111113",
+	}
+	DB.Model(&user).Association("CreditCard").Replace(&creditcard3)
+
+	if creditcard3.ID == 0 {
+		t.Errorf("Creditcard should has ID when created with Replace")
+	}
+
+	var creditcard31 CreditCard
+	DB.Model(&user).Related(&creditcard31)
+	if creditcard31.Number != "411111111113" {
+		t.Errorf("CreditCard should be updated with Replace")
+	}
+
+	// Delete
+	// Clear
 }
 
 func TestRelated(t *testing.T) {