Java JDBC多次插入和一般最佳实践

Question

I have started to learn the JDBC as i want a plugin i am creating to connect with a database, i have it working right now but one thing i don't like is i have an insert query within a for loop which of course is bad. How would i achieve the same thing but with only one query? and also is the rest of my queries okay as in practise wise

open(); // opens a connection from a method
try{
    PreparedStatement sql =  con.prepareStatement("INSERT INTO `score` (player, score) VALUES (?,?);");
    sql.setString(1, "test");
    sql.setInt(2, 1);
    sql.execute();
    sql.close();
}catch(Exception e){
    e.printStackTrace();
}

try{
    PreparedStatement s = con.prepareStatement("SELECT COUNT(*) AS rowcount FROM score"); // get the number of rows
    ResultSet r = s.executeQuery();
    r.next();
    int count = r.getInt("rowcount") / 2; // divide total rows by 2
    int q = Math.round(count);
    r.close();
    s.close();
    PreparedStatement ss = con.prepareStatement("SELECT id FROM score ORDER BY score DESC LIMIT ?;"); // get the top half of results with the highest scores
    ss.setInt(1, q);
    ResultSet rs = ss.executeQuery();

    while(rs.next()){
    PreparedStatement qq = con.prepareStatement("INSERT INTO `round2` (player, score) VALUES (?,?);"); //this is the insert query
    qq.setString(1, rs.getString("player"));
    qq.setInt(2, 0);
    qq.execute();
    qq.close();
    }

    rs.close();
    ss.close();
}catch(Exception e){
    e.printStackTrace();
}
    close(); //close connection

Answer 1

You can use updateBatch on the Statement/PreparedStatement- this way, you can batch the inserts into the database instead of sending in so many inserts into the database as separate jobs.

For instance:

import java.sql.Connection;
import java.sql.PreparedStatement;

//...

String sql = "insert into score (player, score) values (?, ?)";
Connection connection = new getConnection();  //use a connection pool
PreparedStatement ps = connection.prepareStatement(sql);  //prefer this over statement

for (Player player: players) {  //in case you need to iterate through a list

    ps.setString(1, player.getName());   //implement this as needed
    ps.setString(2, player.getScore());   //implement this as needed
    ps.addBatch();  //add statement to batch
}
ps.executeBatch();  //execute batch
ps.close();  //close statement
connection.close();  //close connection (use a connection pool)

Hope it helps