SQL database not populating via Java by using execute/addBatch

Question

I currently have a very large file which contains a few million lines of entries, and want them inserted into a database. The connection established from java to SQL works as I have tried inserting the data singularly and it works, however, when I switched to using executeBatch and addBatch, it seems to loop though but not populating anything into my database.

Code is as follows:

import java.io.BufferedReader;
import java.io.FileReader;
import java.sql.Connection;
import java.sql.DatabaseMetaData;
import java.sql.DriverManager;
import java.sql.SQLException;

public class fedOrganiser6 {
    private static String directory = "C:\\Users\\x\\Desktop\\Files\\";
    private static String file = "combined.fed";
    private static String mapperValue = "";

    public static void main(String[] args) throws Exception {

        Connection conn = null;

        try {
            BufferedReader mapper = new BufferedReader(new FileReader(directory + file));
            String dbURL = "jdbc:sqlserver://localhost\\SQLExpress;database=TIMESTAMP_ORGANISER;integratedSecurity=true";
            String user = "sa";
            String pass = "password";
            conn = DriverManager.getConnection(dbURL, user, pass);
            if (conn != null) {
                DatabaseMetaData dm = (DatabaseMetaData) conn.getMetaData();
                System.out.println("Driver name: " + dm.getDriverName());
                System.out.println("Driver version: " + dm.getDriverVersion());
                System.out.println("Product name: " + dm.getDatabaseProductName());
                System.out.println("Product version: " + dm.getDatabaseProductVersion());
                System.out.println("clearing database");
                conn.createStatement().executeUpdate("truncate table TimestampsStorage");
                System.out.println("bulk insert into database");
                System.out.println("complete");
                int i = 0;
                int records = 0;
                String query = "INSERT INTO TimestampsStorage " + "values(" + "'" + mapperValue.toString() + "'"+ ")";
                conn.prepareStatement(query);
                for (mapperValue = mapper.readLine(); mapperValue != null; mapperValue = mapper.readLine()) {
                    i++;
                    records++;
                    System.out.println("Batching " + records + " records...");

                    conn.createStatement().addBatch(query);
                    if (i == 100000) {
                        conn.createStatement().executeBatch();
                        i = 0;
                    }
                }
            }
            conn.createStatement().executeBatch();
            conn.createStatement().close();
            System.out.print("Done");

        } catch (SQLException ex) {
            ex.printStackTrace();
        } finally {
            try {
                if (conn != null && !conn.isClosed()) {
                    conn.close();
                }
            } catch (SQLException ex) {
                ex.printStackTrace();
            }
        }

    }
}

Answer 1

createStatement() creates a new statement object, so you're execute a different statement than the one you're batching on. You should create the PreparedStatement once, add several batches to it, and then execute on the same object:

String query = "INSERT INTO TimestampsStorage VALUES (?)";
PreparedStatement ps = conn.prepareStatement(query);
for (mapperValue = mapper.readLine(); 
     mapperValue != null; 
     mapperValue = mapper.readLine()) {

    i++;
    records++;
    System.out.println("Batching " + records + " records...");

    ps.setString(1, mapperValue);
    ps.addBatch();

    if (i == 100000) {
        ps.executeBatch();
        i = 0;
    }
}