feat: add Class, ClassStudent, ClassTeacher entities

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

@@ -0,0 +1,47 @@
+import {
+  Entity,
+  PrimaryGeneratedColumn,
+  Column,
+  CreateDateColumn,
+  ManyToOne,
+  JoinColumn,
+  Unique,
+} from 'typeorm';
+import { Class } from './class.entity';
+import { Student } from './student.entity';
+
+@Entity('class_student')
+@Unique(['classId', 'studentId'])
+export class ClassStudent {
+  @PrimaryGeneratedColumn()
+  id: number;
+
+  @Column({ name: 'class_id', type: 'integer' })
+  classId: number;
+
+  @ManyToOne(() => Class, { onDelete: 'CASCADE' })
+  @JoinColumn({ name: 'class_id' })
+  class: Class;
+
+  @Column({ name: 'student_id', type: 'integer' })
+  studentId: number;
+
+  @ManyToOne(() => Student)
+  @JoinColumn({ name: 'student_id' })
+  student: Student;
+
+  @Column({ name: 'enrollment_id', type: 'integer', nullable: true })
+  enrollmentId: number;
+
+  @Column({ name: 'join_date', type: 'date', nullable: true })
+  joinDate: string;
+
+  @Column({ name: 'leave_date', type: 'date', nullable: true })
+  leaveDate: string;
+
+  @Column({ name: 'status', length: 10, default: 'active' })
+  status: string;
+
+  @CreateDateColumn({ name: 'created_at' })
+  createdAt: Date;
+}