CONCUR_READ_ONLY - Learn Java by Examples

How do I know the current position of cursor?

By Wayan in JDBC Last modified: July 28, 2023 0 Comment

Moving through the result set, you might want to know in what row is the current cursor positioned. To get this information, you can call the ResultSet’s getRow() method.

package org.kodejava.jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class ScrollableGetRowExample {
    private static final String URL = "jdbc:mysql://localhost/kodejava";
    private static final String USERNAME = "kodejava";
    private static final String PASSWORD = "s3cr*t";

    public static void main(String[] args) {
        try (Connection connection =
                     DriverManager.getConnection(URL, USERNAME, PASSWORD)) {

            Statement statement = connection.createStatement(
                    ResultSet.TYPE_SCROLL_INSENSITIVE,
                    ResultSet.CONCUR_READ_ONLY);

            String sql = "SELECT id, code, name, price FROM product";
            ResultSet resultSet = statement.executeQuery(sql);
            while (resultSet.next()) {
                String code = resultSet.getString("code");

                // By calling the getRow() method of the result set, we
                // know what is the current row in the result set that
                // we are reading the data from.
                int row = resultSet.getRow();

                System.out.println(row + ". " + code);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

The result of the code snippet above:

1. P0000001
2. P0000002
3. P0000003
4. P0000004
5. P0000005

Maven Dependencies

<dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
    <version>8.1.0</version>
</dependency>

How do I check if a cursor is in the last row?

By Wayan in JDBC Last modified: July 27, 2023 0 Comment

On the previous example, we check for the beginning of the result-set. Now using the isAfterLast() method we can check the opposite whether the pointer is at the end of the result set.

package org.kodejava.jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class ScrollableAfterLastExample {
    private static final String URL = "jdbc:mysql://localhost/kodejava";
    private static final String USERNAME = "kodejava";
    private static final String PASSWORD = "s3cr*t";

    public static void main(String[] args) {
        try (Connection connection =
                     DriverManager.getConnection(URL, USERNAME, PASSWORD)) {

            Statement statement = connection.createStatement(
                    ResultSet.TYPE_SCROLL_INSENSITIVE,
                    ResultSet.CONCUR_READ_ONLY);

            String sql = "SELECT id, code, name, price FROM product";
            ResultSet resultSet = statement.executeQuery(sql);

            // Let's jump to the last records. The afterLast() method will
            // position the cursor after the last record.
            resultSet.afterLast();

            while (resultSet.previous()) {
                long id = resultSet.getLong("id");
                String code = resultSet.getString("code");
                String name = resultSet.getString("name");
                double price = resultSet.getDouble("price");

                System.out.println(id + "\t" + code + "\t" + name + "\t" + price);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

Maven Dependencies

<dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
    <version>8.1.0</version>
</dependency>

How do I check if a cursor is in the first row?

By Wayan in JDBC Last modified: July 27, 2023 0 Comment

When iterating the scrollable result-sets, you can check whether you are in the beginning of the result set or not. The isBeforFirst() method check if the position is at the beginning, if yes this method returns true, otherwise it will return false.

package org.kodejava.jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class ScrollableIsBeforeFirstExample {
    private static final String URL = "jdbc:mysql://localhost/kodejava";
    private static final String USERNAME = "kodejava";
    private static final String PASSWORD = "s3cr*t";

    public static void main(String[] args) {
        try (Connection connection =
                     DriverManager.getConnection(URL, USERNAME, PASSWORD)) {

            Statement statement = connection.createStatement(
                    ResultSet.TYPE_SCROLL_INSENSITIVE,
                    ResultSet.CONCUR_READ_ONLY);

            String sql = "SELECT id, code, name, price FROM product";
            ResultSet resultSet = statement.executeQuery(sql);

            // Using the isBeforeFirst() method we can check if we are at
            // the beginning of the result set.
            if (resultSet.isBeforeFirst()) {
                System.out.println("You are at the beginning of the " +
                                   "result set.");
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

Maven Dependencies

<dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
    <version>8.1.0</version>
</dependency>

How do I move a cursor to the last record?

By Wayan in JDBC Last modified: July 27, 2023 0 Comment

To move the cursor to the end of result-set (after the last record), you can call the afterLast() method of the ResultSet.

package org.kodejava.jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class ScrollableAfterLastExample {
    private static final String URL = "jdbc:mysql://localhost/kodejava";
    private static final String USERNAME = "kodejava";
    private static final String PASSWORD = "s3cr*t";

    public static void main(String[] args) {
        try (Connection connection =
                     DriverManager.getConnection(URL, USERNAME, PASSWORD)) {

            Statement statement = connection.createStatement(
                    ResultSet.TYPE_SCROLL_INSENSITIVE,
                    ResultSet.CONCUR_READ_ONLY);

            String sql = "SELECT code, name, price FROM products";
            ResultSet resultSet = statement.executeQuery(sql);

            // Let's jump to the last records. The afterLast() method will
            // position the cursor after the last record.
            resultSet.afterLast();

            while (resultSet.previous()) {
                String code = resultSet.getString("code");
                String name = resultSet.getString("name");
                double price = resultSet.getDouble("price");

                System.out.println(code + "\t" + name + "\t" + price);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

Maven Dependencies

<dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
    <version>8.1.0</version>
</dependency>

How do I move a cursor in scrollable ResultSet?

By Wayan in JDBC Last modified: July 27, 2023 0 Comment

package org.kodejava.jdbc;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Statement;

public class ScrollableMoveExample {
    private static final String URL = "jdbc:mysql://localhost/kodejava";
    private static final String USERNAME = "kodejava";
    private static final String PASSWORD = "s3cr*t";

    public static void main(String[] args) {
        try (Connection connection =
                     DriverManager.getConnection(URL, USERNAME, PASSWORD)) {

            // In this example, we first create a statement that allows us
            // to go back and forth in the result-set object. First, we'll
            // iterate the result from beginning to the end.
            Statement statement = connection.createStatement(
                    ResultSet.TYPE_SCROLL_INSENSITIVE,
                    ResultSet.CONCUR_READ_ONLY);

            String sql = "SELECT id, code, name, price FROM product";
            ResultSet resultSet = statement.executeQuery(sql);
            while (resultSet.next()) {
                print(resultSet);
            }

            System.out.println();

            // Now the result set pointer is placed after the last record.
            // With the previous method of the result-set, we can now move
            // the pointer backward to the beginning of the result set.
            while (resultSet.previous()) {
                print(resultSet);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }

    private static void print(ResultSet resultSet) throws SQLException {
        long id = resultSet.getLong("id");
        String code = resultSet.getString("code");
        String name = resultSet.getString("name");
        double price = resultSet.getDouble("price");

        System.out.println(id + "\t" + code + "\t" + name + "\t" + price);
    }
}

Here are some results of our program.

1   P0000001    Java 2 Notebook 25.0
2   P0000002    Java Servlet Programming    30.0
3   P0000003    PHP Programming 20.0
4   P0000004    Longman Active Study Dictionary 40.0
5   P0000005    Ruby on Rails   24.0

5   P0000005    Ruby on Rails   24.0
4   P0000004    Longman Active Study Dictionary 40.0
3   P0000003    PHP Programming 20.0
2   P0000002    Java Servlet Programming    30.0
1   P0000001    Java 2 Notebook 25.0

Maven Dependencies

<dependency>
    <groupId>com.mysql</groupId>
    <artifactId>mysql-connector-j</artifactId>
    <version>8.1.0</version>
</dependency>