How do I know if a database supports scrollable result sets?

By Wayan in JDBC 0 Comment 
package org.kodejava.jdbc;

import java.sql.*;

public class SupportScrollableResultSet {
    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)) {
            DatabaseMetaData meta = connection.getMetaData();

            boolean isForwardOnly = meta.supportsResultSetType(
                    ResultSet.TYPE_FORWARD_ONLY);
            System.out.println("ForwardOnly = " + isForwardOnly);

            boolean isScrollInsensitive = meta.supportsResultSetType(
                    ResultSet.TYPE_SCROLL_INSENSITIVE);
            System.out.println("ScrollInsensitive = " + isScrollInsensitive);

            boolean isScrollSensitive = meta.supportsResultSetType(
                    ResultSet.TYPE_SCROLL_SENSITIVE);
            System.out.println("ScrollSensitive = " + isScrollSensitive);
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

The result of the code snippet above:

ForwardOnly = true
ScrollInsensitive = true
ScrollSensitive = false

Maven Dependencies

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

Maven Central

How do I create a scrollable result sets?

By Wayan in JDBC 0 Comment

Since JDBC 2.0 (JDK 1.2), a scrollable ResultSet was introduced to the java.sql API family. Using this ResultSet enables us to navigate the result set in forward or backward way.

To enable the scrollable ResultSet, we need to create a statement object by defining the ResultSet type (ResultSet.TYPE_SCROLL_SENSITIVE, ResultSet.TYPE_SCROLL_INSENSITIVE). If you define the ResultSet type to ResultSet.TYPE_FORWARD_ONLY then you get a regular ResultSet where you can move forward only as in JDBC 1.0

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 ScrollableResultSetExample {
    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);

            // This result set is a scrollable result set
            String query = "SELECT * FROM product";
            ResultSet resultSet = statement.executeQuery(query);
            while (resultSet.next()) {
                System.out.println(resultSet.getString("code"));
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
    }
}

Maven Dependencies

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

Maven Central

How do I know the current position of cursor?

By Wayan in JDBC 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>

Maven Central

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

By Wayan in JDBC 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>

Maven Central

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

By Wayan in JDBC 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>

Maven Central