diff --git a/cmd/import_csv/import_csv.go b/cmd/import_csv/import_csv.go
index cb789eb..6a28fa0 100644
--- a/cmd/import_csv/import_csv.go
+++ b/cmd/import_csv/import_csv.go
@@ -14,8 +14,6 @@ import (
 	"jcourse_go/model/po"
 )
 
-const Semester = "2024-2025-1"
-
 var (
 	db                         *gorm.DB
 	baseCourseKeyMap           = make(map[string]po.BaseCoursePO)
@@ -35,11 +33,35 @@ func main() {
 	dal.InitDBClient()
 	db = dal.GetDBClient()
 
+	// import first level
 	queryAllBaseCourse()
 	readCSV("./data/base_course.csv", importBaseCourse)
 	queryAllTeacher()
 	readCSV("./data/teacher.csv", importTeacher)
-	// queryAllCourse()
+
+	// refresh
+	queryAllBaseCourse()
+	queryAllTeacher()
+
+	// import second level
+	queryAllCourse()
+	readCSV("./data/course.csv", importCourse)
+
+	// refresh
+	queryAllCourse()
+	queryAllOfferedCourse()
+
+	// import
+	readCSV("./data/offered_course.csv", importOfferedCourse)
+
+	// refresh
+	queryAllOfferedCourse()
+	queryAllOfferedCourseCategory()
+	queryAllOfferedCourseTeacherGroup()
+
+	// import
+	readCSV("./data/offered_course_category.csv", importOfferedCourseCategory)
+	readCSV("./data/offered_course_teacher_group.csv", importOfferedCourseTeacherGroup)
 }
 
 func makeBaseCourseKey(courseCode string) string {
@@ -113,7 +135,7 @@ func queryAllOfferedCourse() {
 		if !ok {
 			continue
 		}
-		offeredCourseKeyMap[makeOfferedCourseKey(course.Code, teacher.Name, Semester)] = offeredCourse
+		offeredCourseKeyMap[makeOfferedCourseKey(course.Code, teacher.Name, offeredCourse.Semester)] = offeredCourse
 	}
 	return
 }
@@ -138,7 +160,7 @@ func queryAllOfferedCourseTeacherGroup() {
 		if !ok {
 			continue
 		}
-		offeredCourseTeacherKeyMap[makeOfferedCourseTeacherKey(course.Code, teacher.Name, Semester)] = offeredCourseTeacher
+		offeredCourseTeacherKeyMap[makeOfferedCourseTeacherKey(course.Code, teacher.Name, offeredCourseTeacher.Semester)] = offeredCourseTeacher
 	}
 	return
 }
@@ -162,7 +184,7 @@ func queryAllOfferedCourseCategory() {
 		if !ok {
 			continue
 		}
-		offeredCourseCategoryMap[makeOfferedCourseCategoryKey(course.Code, teacher.Name, offeredCourseCategory.Category, Semester)] = offeredCourseCategory
+		offeredCourseCategoryMap[makeOfferedCourseCategoryKey(course.Code, teacher.Name, offeredCourseCategory.Category, offeredCourseCategory.Semester)] = offeredCourseCategory
 	}
 	return
 }
@@ -224,3 +246,143 @@ func generatePinyinAbbr(name string) string {
 	result := pinyin2.LazyPinyin(name, pinyin2.Args{Style: pinyin2.FirstLetter})
 	return strings.Join(result, "")
 }
+
+func importCourse(data [][]string) {
+	newCourses := make([]po.CoursePO, 0)
+	for _, line := range data {
+		courseCode := line[0]
+		teacherCode := line[1]
+		baseCourse, ok := baseCourseKeyMap[makeBaseCourseKey(courseCode)]
+		if !ok {
+			continue
+		}
+		teacher, ok := teacherKeyMap[makeTeacherKey(teacherCode)]
+		if !ok {
+			continue
+		}
+		if _, exists := courseKeyMap[makeCourseKey(courseCode, teacher.Name)]; exists {
+			continue
+		}
+		course := po.CoursePO{
+			Code:            baseCourse.Code,
+			Name:            baseCourse.Name,
+			Credit:          baseCourse.Credit,
+			BaseCourseID:    int64(baseCourse.ID),
+			MainTeacherID:   int64(teacher.ID),
+			MainTeacherName: teacher.Name,
+		}
+		newCourses = append(newCourses, course)
+	}
+	println("new course length:", len(newCourses))
+	db.Model(&po.CoursePO{}).CreateInBatches(&newCourses, 100)
+}
+
+func importOfferedCourse(data [][]string) {
+	newOfferedCourses := make([]po.OfferedCoursePO, 0)
+	for _, line := range data {
+		courseCode := line[0]
+		teacherCode := line[1]
+		semester := line[2]
+		teacher, ok := teacherKeyMap[makeTeacherKey(teacherCode)]
+		if !ok {
+			continue
+		}
+
+		course, ok := courseKeyMap[makeCourseKey(courseCode, teacher.Name)]
+		if !ok {
+			continue
+		}
+
+		if _, exists := offeredCourseKeyMap[makeOfferedCourseKey(courseCode, teacher.Name, semester)]; exists {
+			continue
+		}
+
+		offeredCourse := po.OfferedCoursePO{
+			CourseID:      int64(course.ID),
+			BaseCourseID:  course.BaseCourseID,
+			MainTeacherID: int64(teacher.ID),
+			Semester:      semester,
+			Department:    line[3],
+			Grade:         line[4],
+			Language:      line[5],
+		}
+		newOfferedCourses = append(newOfferedCourses, offeredCourse)
+	}
+	println("new offered course length:", len(newOfferedCourses))
+	db.Model(&po.OfferedCoursePO{}).CreateInBatches(&newOfferedCourses, 100)
+}
+
+func importOfferedCourseCategory(data [][]string) {
+	newOfferedCourseCategories := make([]po.OfferedCourseCategoryPO, 0)
+	for _, line := range data {
+		courseCode := line[0]
+		teacherCode := line[1]
+		semester := line[2]
+		category := line[3]
+		teacher, ok := teacherKeyMap[makeTeacherKey(teacherCode)]
+		if !ok {
+			continue
+		}
+
+		offeredCourse, ok := offeredCourseKeyMap[makeOfferedCourseKey(courseCode, teacher.Name, semester)]
+		if !ok {
+			continue
+		}
+
+		if _, exists := offeredCourseCategoryMap[makeOfferedCourseCategoryKey(courseCode, teacher.Name, category, semester)]; exists {
+			continue
+		}
+
+		offeredCourseCategory := po.OfferedCourseCategoryPO{
+			CourseID:        offeredCourse.CourseID,
+			BaseCourseID:    offeredCourse.BaseCourseID,
+			MainTeacherID:   int64(teacher.ID),
+			OfferedCourseID: int64(offeredCourse.ID),
+			Category:        category,
+		}
+		newOfferedCourseCategories = append(newOfferedCourseCategories, offeredCourseCategory)
+	}
+	println("new offered course category length:", len(newOfferedCourseCategories))
+	db.Model(&po.OfferedCourseCategoryPO{}).CreateInBatches(&newOfferedCourseCategories, 100)
+}
+
+func importOfferedCourseTeacherGroup(data [][]string) {
+	newOfferedCourseTeachers := make([]po.OfferedCourseTeacherPO, 0)
+	for _, line := range data {
+		courseCode := line[0]
+		mainTeacherCode := line[1]
+		semester := line[2]
+
+		mainTeacher, ok := teacherKeyMap[makeTeacherKey(mainTeacherCode)]
+		if !ok {
+			continue
+		}
+
+		offeredCourse, ok := offeredCourseKeyMap[makeOfferedCourseKey(courseCode, mainTeacher.Name, semester)]
+		if !ok {
+			continue
+		}
+
+		thisTeacherCode := line[3]
+		thisTeacher, ok := teacherKeyMap[makeTeacherKey(thisTeacherCode)]
+		if !ok {
+			continue
+		}
+
+		if _, exists := offeredCourseTeacherKeyMap[makeOfferedCourseTeacherKey(courseCode, thisTeacher.Name, semester)]; exists {
+			continue
+		}
+
+		offeredCourseTeacher := po.OfferedCourseTeacherPO{
+			CourseID:        offeredCourse.CourseID,
+			BaseCourseID:    offeredCourse.BaseCourseID,
+			MainTeacherID:   int64(mainTeacher.ID),
+			OfferedCourseID: int64(offeredCourse.ID),
+			TeacherID:       int64(thisTeacher.ID),
+			TeacherName:     thisTeacher.Name,
+		}
+		newOfferedCourseTeachers = append(newOfferedCourseTeachers, offeredCourseTeacher)
+	}
+	println("new offered course teacher length:", len(newOfferedCourseTeachers))
+	db.Model(&po.OfferedCourseTeacherPO{}).CreateInBatches(&newOfferedCourseTeachers, 100)
+}
diff --git a/model/po/course.go b/model/po/course.go
index bae82d0..19863ba 100644
--- a/model/po/course.go
+++ b/model/po/course.go
@@ -6,9 +6,9 @@ type CoursePO struct {
 	gorm.Model
 	Code            string  `gorm:"index"`
 	Name            string  `gorm:"index"`
-	Credit          float32 `gorm:"index"`
-	BaseCourseID    int64   `gorm:"index"`
-	MainTeacherID   int64   `gorm:"index"`
+	Credit          float64 `gorm:"index"`
+	BaseCourseID    int64   `gorm:"index;index:uniq_course,unique"`
+	MainTeacherID   int64   `gorm:"index;index:uniq_course,unique"`
 	MainTeacherName string  `gorm:"index"`
 }
 
@@ -19,9 +19,9 @@ func (po *CoursePO) TableName() string {
 type OfferedCoursePO struct {
 	gorm.Model
 	BaseCourseID  int64  `gorm:"index"`
-	CourseID      int64  `gorm:"index"`
-	MainTeacherID int64  `gorm:"index"`
-	Semester      string `gorm:"index"`
+	CourseID      int64  `gorm:"index;index:uniq_offered_course,unique"`
+	MainTeacherID int64  `gorm:"index;index:uniq_offered_course,unique"`
+	Semester      string `gorm:"index;index:uniq_offered_course,unique"`
 	Department    string `gorm:"index"`
 	Language      string `gorm:"index"`
 	Grade         string `gorm:"index"`
@@ -35,9 +35,11 @@ type OfferedCourseTeacherPO struct {
 	gorm.Model
 	BaseCourseID    int64  `gorm:"index"`
 	CourseID        int64  `gorm:"index"`
-	OfferedCourseID int64  `gorm:"index"`
-	TeacherID       int64  `gorm:"index"`
+	OfferedCourseID int64  `gorm:"index;index:uniq_offered_course_teacher,unique"`
+	MainTeacherID   int64  `gorm:"index"`
+	TeacherID       int64  `gorm:"index;index:uniq_offered_course_teacher,unique"`
 	TeacherName     string `gorm:"index"`
+	Semester        string `gorm:"index;index:uniq_offered_course_teacher,unique"`
 }
 
 func (po *OfferedCourseTeacherPO) TableName() string {
@@ -48,9 +50,10 @@ type OfferedCourseCategoryPO struct {
 	gorm.Model
 	BaseCourseID    int64  `gorm:"index"`
 	CourseID        int64  `gorm:"index"`
-	OfferedCourseID int64  `gorm:"index"`
+	OfferedCourseID int64  `gorm:"index;index:uniq_offered_course_category,unique"`
 	MainTeacherID   int64  `gorm:"index"`
-	Category        string `gorm:"index"`
+	Category        string `gorm:"index;index:uniq_offered_course_category,unique"`
+	Semester        string `gorm:"index;index:uniq_offered_course_category,unique"`
 }
 
 func (po *OfferedCourseCategoryPO) TableName() string {
@@ -59,10 +62,10 @@ func (po *OfferedCourseCategoryPO) TableName() string {
 
 type TrainingPlanPO struct {
 	gorm.Model
-	Degree     string `gorm:"index"`
-	Major      string `gorm:"index"`
-	Department string `gorm:"index"`
-	EntryYear  string `gorm:"index"`
+	Degree     string `gorm:"index;index:uniq_training_plan,unique"`
+	Major      string `gorm:"index;index:uniq_training_plan,unique"`
+	Department string `gorm:"index;index:uniq_training_plan,unique"`
+	EntryYear  string `gorm:"index;index:uniq_training_plan,unique"`
 }
 
 func (po *TrainingPlanPO) TableName() string {
@@ -71,8 +74,8 @@ func (po *TrainingPlanPO) TableName() string {
 
 type TrainingPlanCoursePO struct {
 	gorm.Model
-	CourseID       int64 `gorm:"index"`
-	TrainingPlanID int64 `gorm:"index"`
+	CourseID       int64 `gorm:"index;index:uniq_training_plan_course,unique"`
+	TrainingPlanID int64 `gorm:"index;index:uniq_training_plan_course,unique"`
 }
 
 func (po *TrainingPlanCoursePO) TableName() string {
@@ -81,7 +84,7 @@ func (po *TrainingPlanCoursePO) TableName() string {
 
 type BaseCoursePO struct {
 	gorm.Model
-	Code   string  `gorm:"index"`
+	Code   string  `gorm:"index;uniqueIndex"`
 	Name   string  `gorm:"index"`
 	Credit float64 `gorm:"index"`
 }
@@ -93,7 +96,7 @@ func (po *BaseCoursePO) TableName() string {
 type TeacherPO struct {
 	gorm.Model
 	Name       string `gorm:"index"`
-	Code       string `gorm:"index"`
+	Code       string `gorm:"index;uniqueIndex"`
 	Department string `gorm:"index"`
 	Title      string
 	Pinyin     string `gorm:"index"`