1

src/ru/milandr/courses/polishchuk/Application.java

@@ -0,0 +1,263 @@
+package ru.milandr.courses.polishchuk;
+
+import com.sun.org.apache.bcel.internal.generic.ARETURN;
+
+import javax.jws.soap.SOAPBinding;
+import java.math.BigDecimal;
+import java.math.BigInteger;
+import java.sql.*;
+import java.util.ArrayList;
+import java.util.Comparator;
+
+class SQLDemo {
+    private Connection connection;
+
+    private class User {
+        BigDecimal id;
+        String first_name;
+        String last_name;
+        String phone_number;
+
+        User(BigDecimal id, String first_name, String last_name, String phone_number) {
+            this.id = id;
+            this.first_name = first_name;
+            this.last_name = last_name;
+            this.phone_number = phone_number;
+        }
+
+        User(User user) {
+            this.id = user.id;
+            this.last_name = user.last_name;
+            this.first_name = user.first_name;
+            this.phone_number = user.phone_number;
+        }
+
+        void printUser() {
+            System.out.print("user id: " + this.id + '\n' +
+                    "first_name: " + this.first_name + '\n' +
+                    "last_name: " + this.last_name + '\n' +
+                    "phone_number: " + this.phone_number + '\n');
+        }
+    }
+
+    private class Address {
+        BigDecimal id;
+        String address;
+        String city;
+        String postal_code;
+
+        Address(BigDecimal id, String address, String city, String postal_code) {
+            this.id = id;
+            this.address = address;
+            this.city = city;
+            this.postal_code = postal_code;
+        }
+
+        void printAddress() {
+            System.out.print("address id: " + this.id + '\n' +
+                    "address: " + this.address + '\n' +
+                    "city: " + this.city + '\n' +
+                    "postal_code: " + this.postal_code + '\n');
+        }
+    }
+
+    private class AddressedUser extends User {
+        Address address;
+
+        AddressedUser(User user, Address address) {
+            super(user);
+            this.address = address;
+        }
+
+        AddressedUser(BigDecimal id, String first_name, String last_name, String phone_number, Address address) {
+            super(id, first_name, last_name, phone_number);
+            this.address = address;
+        }
+
+        @Override
+        void printUser() {
+            super.printUser();
+            this.address.printAddress();
+        }
+    }
+
+    public SQLDemo(Connection connection) {
+        this.connection = connection;
+    }
+
+    public Connection getConnection() {
+        return connection;
+    }
+
+    private void printUsers(ArrayList<User> users) {
+        for (User user : users) {
+            user.printUser();
+        }
+    }
+
+    private User initUserFromResultSet(ResultSet user) throws SQLException {
+        return new User(
+                user.getBigDecimal("id"),
+                user.getString("first_name"),
+                user.getString("last_name"),
+                user.getString("phone_number")
+        );
+    }
+
+    private Address initAddressFromResultSet(ResultSet address) throws SQLException {
+        return new Address(
+                address.getBigDecimal("address_id"),
+                address.getString("address"),
+                address.getString("city"),
+                address.getString("postal_code")
+        );
+    }
+
+    private AddressedUser initAddressedUserFromResultSet(ResultSet user) throws SQLException {
+        return new AddressedUser(
+                initUserFromResultSet(user),
+                initAddressFromResultSet(user)
+        );
+    }
+
+    private void printUserWithIdJava(BigDecimal id) {
+        try (PreparedStatement stmtSelectUsersIds = connection.prepareStatement(
+                "select users.*, addresses.id as addr_id, address, city, postal_code " +
+                        "from users " +
+                        "join addresses on users.address_id = addresses.id " +
+                        "where users.id = ?"
+        )) {
+            stmtSelectUsersIds.setBigDecimal(1, id);
+
+            ResultSet user = stmtSelectUsersIds.executeQuery();
+            if (!user.next())
+                throw new SQLException("Zero users found!");
+            if (!user.isLast())
+                throw new SQLException("Duplicate user id found!");
+            AddressedUser userWithId = initAddressedUserFromResultSet(user);
+            userWithId.printUser();
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+    }
+
+    public void printUserWithMaxIdJava() {
+        try (PreparedStatement stmtSelectUsersIds = connection.prepareStatement("select id from users")) {
+            BigDecimal maxId = new BigDecimal(-1);
+            ResultSet userIds = stmtSelectUsersIds.executeQuery();
+
+            while (userIds.next()) {
+                BigDecimal id = userIds.getBigDecimal("id");
+                if (maxId.compareTo(id) < 0) {
+                    maxId = new BigDecimal(String.valueOf(id));
+                }
+            }
+            printUserWithIdJava(maxId);
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+    }
+
+    public void printUsersFromAddress(String address) {
+        try (PreparedStatement stmtSelectUsersFromAddress = connection.prepareStatement(
+                "select users.*, a.id as address_id, address, city, postal_code " +
+                        "from users join addresses a on users.address_id = a.id " +
+                        "where address = ?"
+        )) {
+            stmtSelectUsersFromAddress.setString(1, address);
+            ResultSet resultSet = stmtSelectUsersFromAddress.executeQuery();
+
+            while (resultSet.next()) {
+                AddressedUser addressedUser = initAddressedUserFromResultSet(resultSet);
+                addressedUser.printUser();
+                System.out.println();
+            }
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+    }
+
+    public void printUsersSortedByLastName() {
+        try (PreparedStatement stmtSelectUsers = connection.prepareStatement("select * from users")) {
+            ResultSet resultSet = stmtSelectUsers.executeQuery();
+
+            ArrayList<User> usersArrayList = new ArrayList<>();
+            while (resultSet.next()) {
+                User user = initUserFromResultSet(resultSet);
+                usersArrayList.add(user);
+            }
+            usersArrayList.sort((o1, o2) -> o1.last_name.compareTo(o2.last_name));
+            usersArrayList.forEach(u -> System.out.println(u.last_name + ' ' + u.first_name));
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+    }
+
+    public double calcAvgPostalCode() {
+        double sum = 0;
+        int cnt = 0;
+
+        try (PreparedStatement stmtSelectPostalCodes = connection.prepareStatement(
+                "select postal_code from addresses"
+        )) {
+            ResultSet resultSet = stmtSelectPostalCodes.executeQuery();
+
+            while (resultSet.next()) {
+                String code = resultSet.getString("postal_code");
+                if (code.matches("^[0-9]+$")) {
+                    sum += Integer.parseInt(code);
+                    cnt++;
+                }
+            }
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+        if (cnt == 0)
+            return 0.;
+        return sum / cnt;
+    }
+
+    public void findUnusedAddr() {
+        try (PreparedStatement stmt = connection.prepareStatement(
+                "select address from addresses left join users on users.address_id = addresses.id where users.id is null"
+        )) {
+            ResultSet resultSet = stmt.executeQuery();
+            if (resultSet.next()){
+                System.out.println(resultSet.getString(1));
+            }
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+    }
+}
+
+public class Application {
+    public static void main(String[] args) throws ClassNotFoundException {
+        try {
+            Class.forName("org.postgresql.Driver");
+        } catch (ClassNotFoundException e) {
+            e.printStackTrace();
+            return;
+        }
+        try (Connection dbConn = DriverManager.getConnection(
+                "jdbc:postgresql://localhost:5432/users_database",
+                "postgres", "postgres")) {
+            SQLDemo demo = new SQLDemo(dbConn);
+
+            demo.printUserWithMaxIdJava();
+            System.out.println();
+
+            demo.printUsersFromAddress("P.O. Box 677, 8665 Ante Road");
+            System.out.println();
+
+            demo.printUsersSortedByLastName();
+            System.out.println();
+
+            System.out.println(demo.calcAvgPostalCode());
+
+            demo.findUnusedAddr();
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+    }
+}

src/ru/milandr/courses/polishchuk/TablesEqualityMain.java

@@ -0,0 +1,38 @@
+package ru.milandr.courses.polishchuk;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.SQLException;
+
+public class TablesEqualityMain {
+    public static void main(String[] args) {
+        try {
+            Class.forName("org.postgresql.Driver");
+        } catch (ClassNotFoundException e) {
+            e.printStackTrace();
+        }
+        try (
+                Connection conn1 = DriverManager.getConnection(
+                        "jdbc:postgresql://localhost:5432/users_database",
+                        "postgres", "postgres"
+                );
+                Connection conn2 = DriverManager.getConnection(
+                        "jdbc:postgresql://localhost:5432/users_database",
+                        "postgres", "postgres"
+                )
+        ) {
+            TablesEqualityTester tester = new TablesEqualityTester(
+                    conn1, conn2,
+                    "users4test", "users4test1",
+                    "id,first_name,last_name"
+            );
+            if (tester.equalityTest()) {
+                System.out.println("Equals");
+            } else {
+                System.out.println("Not equal");
+            }
+        } catch (SQLException e) {
+            e.printStackTrace();
+        }
+    }
+}