Added queries for S2 (MySQL).

Practical/Practical Exam/SQL/S2 - SQL Queries.md

@@ -0,0 +1,159 @@
+# S2 - SQL Queries (in MySQL)
+
+**Problem Statement:**
+Consider following Relation
+Account (Acc_no, branch_name,balance)
+Branch(branch_name,branch_city,assets)
+Customer(cust_name,cust_street,cust_city)
+Depositor(cust_name,acc_no)
+Loan(loan_no,branch_name,amount)
+Borrower(cust_name,loan_no)
+Create above tables with appropriate constraints like primary key,
+foreign key, not null etc.
+1. Find all customers who have both account and loan at bank.
+2. Find all customers who have an account or loan or both at bank.
+3. Find all customers who have account but no loan at the bank.
+4. Find average account balance at ‘Wadia College’ branch.
+5. Find no. of depositors at each branch
+
+---
+
+## Creating the database
+```sql
+CREATE DATABASE Bank2;
+USE Bank2;
+
+```
+
+## Creating tables:
+
+```sql
+CREATE TABLE Account (
+  acc_no INT,
+  branch_name VARCHAR(255),
+  balance INT,
+  PRIMARY KEY (acc_no)
+);
+
+CREATE TABLE Branch (
+  branch_name VARCHAR(255),
+  branch_city VARCHAR(255),
+  assets INT,
+  PRIMARY KEY (branch_name)
+);
+
+CREATE TABLE Customer (
+  cust_name VARCHAR(255),
+  cust_street VARCHAR(255),
+  cust_city VARCHAR(255),
+  PRIMARY KEY (cust_name)
+);
+
+CREATE TABLE Depositor (
+  cust_name VARCHAR(255),
+  acc_no INT
+);
+
+CREATE TABLE Loan (
+  loan_no INT,
+  branch_name VARCHAR(255),
+  amount INT,
+  PRIMARY KEY (loan_no)
+);
+
+CREATE TABLE Borrower (
+  cust_name VARCHAR(255),
+  loan_no INT
+);
+
+```
+
+## Declaring foreign keys
+
+```sql
+ALTER TABLE Account ADD FOREIGN KEY (branch_name) REFERENCES Branch (branch_name);
+ALTER TABLE Depositor ADD FOREIGN KEY (cust_name) REFERENCES Customer (cust_name);
+ALTER TABLE Depositor ADD FOREIGN KEY (acc_no) REFERENCES Account (acc_no);
+ALTER TABLE Loan ADD FOREIGN KEY (branch_name) REFERENCES Branch (branch_name);
+ALTER TABLE Borrower ADD FOREIGN KEY (cust_name) REFERENCES Customer (cust_name);
+ALTER TABLE Borrower ADD FOREIGN KEY (loan_no) REFERENCES Loan (loan_no);
+
+```
+
+## Inserting data
+
+```sql
+INSERT INTO Branch VALUES
+('Wadia College', 'Pune', 50000),
+('PES', 'Pune', 65000),
+('Lohegaon', 'Pune', 350000),
+('Viman Nagar', 'Pune', 850000);
+
+INSERT INTO Customer VALUES
+('Kalas', 'Street 12', 'Pune'),
+('Himanshu', 'Street 15', 'Pune'),
+('Mehul', 'Street 29', 'Pune'),
+('Macho', 'Street 59', 'Mumbai'),
+('Gundeti', 'Street 40', 'Mumbai'),
+('Salvi', 'Street 8', 'Pune');
+
+INSERT INTO Account VALUES
+(101, 'Lohegaon', 5500),
+(102, 'PES', 4324),
+(103, 'PES', 5467),
+(104, 'Viman Nagar', 5433),
+(105, 'Wadia College', 6462);
+
+INSERT INTO Depositor VALUES
+('Kalas', 101),
+('Macho', 104),
+('Gundeti', 105),
+('Salvi', 105);
+
+INSERT INTO Loan VALUES
+(201, 'Wadia College', 18000),
+(202, 'PES', 8500),
+(203, 'PES', 15000),
+(204, 'Wadia College', 5322);
+
+INSERT INTO Borrower VALUES
+('Macho', 201),
+('Mehul', 202),
+('Himanshu', 203),
+('Salvi', 204);
+
+```
+
+## Queries
+
+1. Find all customers who have both account and loan at bank.
+```sql
+SELECT cust_name FROM Depositor INTERSECT SELECT cust_name FROM Borrower;
+
+```
+
+2. Find all customers who have an account or loan or both at bank.
+```sql
+SELECT cust_name FROM Depositor UNION SELECT cust_name FROM Borrower;
+
+```
+
+3. Find all customers who have account but no loan at the bank.
+```sql
+SELECT cust_name FROM Depositor WHERE cust_name NOT IN (SELECT cust_name FROM Borrower);
+
+```
+
+4. Find average account balance at ‘Wadia College’ branch.
+```sql
+SELECT AVG(balance) FROM Account WHERE branch_name = 'Wadia College';
+
+```
+
+5. Find no. of depositors at each branch
+```sql
+SELECT Account.branch_name, COUNT(*) AS total FROM Account INNER JOIN Depositor ON Account.acc_no = Depositor.acc_no GROUP BY branch_name;
+
+```
+
+---