Added queries for S9 (MySQL).

Practical/Practical Exam/S9 - SQL Queries.md

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+# S9 - SQL Queries (in MySQL)
+
+**Problem Statement:**
+SQL Queries
+Create following tables with suitable constraints. Insert data and
+solve the following queries:
+CUSTOMERS(_CNo_, Cname, Ccity, CMobile)
+ITEMS(_INo_, Iname, Itype, Iprice, Icount)
+PURCHASE(_PNo_, Pdate, Pquantity, Cno, INo)
+1. List all stationary items with price between 400/- to 1000/-
+2. Change the mobile number of customer “Gopal”
+3. Display the item with maximum price
+4. Display all purchases sorted from the most recent to the oldest
+5. Count the number of customers in every city
+6. Display all purchased quantity of Customer Maya
+7. Create view which shows Iname, Price and Count of all stationary
+items in descending order of price.
+
+---
+
+## Creating the database
+```sql
+CREATE DATABASE Store3;
+USE Store3;
+
+```
+
+## Creating tables:
+
+```sql
+CREATE TABLE Customers (
+  CNo INT,
+  Cname VARCHAR(255),
+  Ccity VARCHAR(255),
+  Cmobile BIGINT,
+  PRIMARY KEY (CNo)
+);
+
+CREATE TABLE Items (
+  INo INT,
+  Iname VARCHAR(255),
+  Itype VARCHAR(255),
+  Iprice INT,
+  Icount INT,
+  PRIMARY KEY (Icount)
+);
+
+CREATE TABLE Purchase (
+  PNo INT,
+  Pdate DATE,
+  Pquantity INT,
+  Cno INT,
+  INo INT,
+  PRIMARY KEY (PNo),
+  FOREIGN KEY (Cno) REFERENCES Customers (CNo)
+);
+
+```
+
+> [!WARNING]
+> Notice inconsistent naming for columns? We're just doing it by the books. Blame the one who made these [problem statements](https://git.kska.io/sppu-te-comp-content/DatabaseManagementSystems/src/branch/main/Practical/Practical%20Exam/DBMSL%20-%20Problem%20Statements%20for%20Practical%20Exam%20%28November%202024%29.pdf).
+
+## Inserting data
+
+```sql
+INSERT INTO Customers VALUES
+(1, 'Kalas', 'Pune', 9857265240),
+(2, 'Himanshu', 'Chennai', 9857265241),
+(3, 'Gopal', 'Mumbai', 9857265245),
+(4, 'Maya', 'Mumbai', 9857265243),
+(5, 'Mehul', 'Pune', 9857265244);
+
+INSERT INTO Items VALUES
+(101, 'Stamp', 'Collectables', 850, 10),
+(102, 'Pen', 'Instruments', 549, 50),
+(103, 'Sticky notes', 'Writing', 150, 200),
+(104, 'Geometry box', 'Instruments', 1350, 70),
+(105, 'Pencil', 'Instruments', 670, 45);
+
+INSERT INTO Purchase VALUES
+(201, '2024-11-05', 4, 1, 101),
+(202, '2024-11-07', 3, 2, 102),
+(203, '2024-11-08', 20, 3, 103),
+(204, '2024-10-29', 1, 4, 104),
+(205, '2024-11-10', 7, 5, 105);
+
+```
+
+## Queries
+
+1. List all stationary items with price between 400/- to 1000/-
+```sql
+SELECT Iname FROM Items WHERE Iprice BETWEEN 400 AND 1000;
+
+```
+
+2. Change the mobile number of customer “Gopal”
+```sql
+UPDATE Customers SET CMobile = 9857265242 WHERE Cname = "Gopal";
+SELECT * FROM Customers WHERE Cname = "Gopal";
+
+```
+
+3. Display the item with maximum price
+```sql
+SELECT Iname FROM Items WHERE Iprice = (SELECT MAX(Iprice) FROM Items);
+
+```
+
+4. Display all purchases sorted from the most recent to the oldest
+```sql
+SELECT * FROM Purchase ORDER BY Pdate DESC;
+
+```
+
+5. Count the number of customers in every city
+```sql
+SELECT COUNT(*), Ccity FROM Customers GROUP BY Ccity;
+
+```
+
+6. Display all purchased quantity of Customer Maya
+```sql
+SELECT Iname, Pquantity FROM Purchase INNER JOIN Customers ON Purchase.Cno = Customers.CNo INNER JOIN Items ON Purchase.INo = Items.INo WHERE Cname = "Maya";
+
+```
+
+7. Create view which shows Iname, Price and Count of all stationary items in descending order of price.
+```sql
+CREATE VIEW itemView AS SELECT Iname, Iprice, COUNT(*) FROM Items GROUP BY Iname, Iprice ORDER BY Iprice DESC;
+SELECT * FROM itemView;
+
+```
+
+---