duplicate customers no longer allowed in queue.

QueueingApp/src/main/java/appQueue/CustomerDAO.java

@@ -23,23 +23,24 @@ public class CustomerDAO extends DAO{
 		int result = 0;
 		
 		try {
-			
-			Connection connection = createConnection();
-			
-			//create a query
-			Statement statement = connection.createStatement();
-			String insert_customer = "INSERT INTO customers (name, email, phone, avgWaiting, position) VALUES (?, ?, ?, ?, ?);";
-			
-			//prepare the statement
-			PreparedStatement prepared_statement = connection.prepareStatement(insert_customer);
-			prepared_statement.setString(1, customer.getName());
-			prepared_statement.setString(2, customer.getEmail());
-			prepared_statement.setString(3, customer.getPhoneNumber());
-			prepared_statement.setString(4, customer.getAvgWaiting().toString());
-			prepared_statement.setString(5, customer.getQueuePosition().toString());
-			
-			//execute query
-			result = prepared_statement.executeUpdate();
+			if (CustomerQueue.doesCostumerExists(customer.getEmail()) == null) {
+				Connection connection = createConnection();
+				
+				//create a query
+				Statement statement = connection.createStatement();
+				String insert_customer = "INSERT INTO customers (name, email, phone, avgWaiting, position) VALUES (?, ?, ?, ?, ?);";
+				
+				//prepare the statement
+				PreparedStatement prepared_statement = connection.prepareStatement(insert_customer);
+				prepared_statement.setString(1, customer.getName());
+				prepared_statement.setString(2, customer.getEmail());
+				prepared_statement.setString(3, customer.getPhoneNumber());
+				prepared_statement.setString(4, customer.getAvgWaiting().toString());
+				prepared_statement.setString(5, customer.getQueuePosition().toString());
+				
+				//execute query
+				result = prepared_statement.executeUpdate();
+			}
 		}
 		catch (SQLException e) {
 			e.printStackTrace();