From 1de09bd5f6264a8427cd7426391b3d85a8ebf82f Mon Sep 17 00:00:00 2001
From: Aadit Agrawal <tech@aaditagrawal.com>
Date: Tue, 4 Feb 2025 16:04:20 +0530
Subject: [PATCH] Update DBMS/SQL/Week5/writeup.md

---
 DBMS/SQL/Week5/writeup.md | 75 ++++++++++++++++++++++++++++++++++++++-
 1 file changed, 74 insertions(+), 1 deletion(-)

diff --git a/DBMS/SQL/Week5/writeup.md b/DBMS/SQL/Week5/writeup.md
index e578dd7..a4d6c8c 100644
--- a/DBMS/SQL/Week5/writeup.md
+++ b/DBMS/SQL/Week5/writeup.md
@@ -425,11 +425,65 @@ DEPT
 ICT
 ```
 
-
 ### Find the students who have enrolled for course of more than one department
 
+```sql
+SQL> select name
+  2  from student
+  3  where regno in(
+  4  select regno
+  5  from enroll natural join course
+  6  group by regno
+  7  having count(distinct dept)>1);
+
+NAME
+--------------------
+Aadit
+```
+
+To create a list, we use
+
+```sql
+SQL> select regno,count(distinct dept)
+  2  from enroll natural join course
+  3  group by regno;
+
+REGNO                COUNT(DISTINCTDEPT)
+-------------------- -------------------
+456                                    2
+101                                    1
+890                                    1
+567                                    1
+123                                    1
+789                                    1
+
+6 rows selected.
+```
+
 ### Produce a list of students who are not enrolled.
 
+```sql
+SQL> select regno,name
+  2  from student
+  3  where regno not in(
+  4  select regno from enroll);
+
+REGNO      NAME
+---------- --------------------
+234        Vansh
+
+SQL>
+SQL> select regno,name
+  2  from student
+  3  where not exists(
+  4  select regno from enroll
+  5  where student.regno=enroll.regno);
+
+REGNO      NAME
+---------- --------------------
+234        Vansh
+```
+
 ### List the department which adopts all the books from the particular publisher
 
 ```sql
@@ -548,3 +602,22 @@ Classmate                           1
 
 ### List the students who enrolled for all the books adopted by their course
 
+```sql
+SQL> select distinct regno
+  2  from enroll natural join student
+  3  where exists
+  4  (select book_isbn
+  5  from book_adoption
+  6  where book_adoption.course#=enroll.course#);
+
+REGNO
+--------------------
+456
+101
+890
+123
+567
+789
+
+6 rows selected.
+```