1、 普通子查询： 1）带有IN谓词的子查询 T3：查询与“刘晨”在同一系学习的学生的学号及姓名，用嵌套查询完成 T4：查询所有选修了1号课程的学生姓名（用连接查询完成） T5：查询所有选修了1号课程的学生姓名（用嵌套查询完成） 全英文

1. **Simple Nested Queries (with IN predicate):**
a) **Query T3**: To find the student IDs and names who study with "Liu Chen" in the same department, you can use an inner query like this:

   SELECT s.student_id, s.name
   FROM students s
   WHERE s.department = (
       SELECT d.department
       FROM departments d
       WHERE d.name = '刘晨所在部门'
   );

b) **Query T4**: To get the names of all students who have taken Course 1, you can use a join query to connect the students and courses tables:

   SELECT sc.student_name
   FROM students sc
   JOIN enrollments e ON sc.student_id = e.student_id
   JOIN courses c ON e.course_id = c.course_id
   WHERE c.course_number = 1;

c) **Query T5** (using nested query): Similar to Query T4 but with a subquery for the course number:

   SELECT sc.student_name
   FROM students sc
   WHERE EXISTS (
       SELECT 1
       FROM courses c
       WHERE c.course_number = 1 AND sc.student_id = c.student_id
   );