# 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;

```

---