feat: add Class, ClassStudent, ClassTeacher entities

apps/server/src/entities/class-teacher.entity.ts

@@ -0,0 +1,48 @@
+import {
+  Entity,
+  PrimaryGeneratedColumn,
+  Column,
+  CreateDateColumn,
+  ManyToOne,
+  JoinColumn,
+  Unique,
+} from 'typeorm';
+import { Class } from './class.entity';
+import { User } from './user.entity';
+
+export enum TeacherRoleType {
+  SUBJECT_TEACHER = 'subject_teacher',
+  HEAD_TEACHER = 'head_teacher',
+  LIFE_TEACHER = 'life_teacher',
+  ACADEMIC_TEACHER = 'academic_teacher',
+}
+
+@Entity('class_teacher')
+@Unique(['classId', 'userId', 'roleType'])
+export class ClassTeacher {
+  @PrimaryGeneratedColumn()
+  id: number;
+
+  @Column({ name: 'class_id', type: 'integer' })
+  classId: number;
+
+  @ManyToOne(() => Class, { onDelete: 'CASCADE' })
+  @JoinColumn({ name: 'class_id' })
+  class: Class;
+
+  @Column({ name: 'user_id', type: 'integer' })
+  userId: number;
+
+  @ManyToOne(() => User)
+  @JoinColumn({ name: 'user_id' })
+  user: User;
+
+  @Column({ name: 'role_type', length: 30 })
+  roleType: string;
+
+  @Column({ name: 'subject', length: 50, nullable: true })
+  subject: string;
+
+  @CreateDateColumn({ name: 'created_at' })
+  createdAt: Date;
+}