Das ist der CoinHanderl

package de.fallenbreak.coinsapi.database;

import de.fallenbreak.coinsapi.CoinsAPI;
import de.fallenbreak.coinsapi.database.container.AsyncMySQL;
import org.bukkit.Bukkit;

import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.UUID;
import java.util.logging.Level;

public class CoinsHandler {

    private final AsyncMySQL sql = CoinsAPI.getInstance().getAsyncMySQL();
    private final String table;

    public CoinsHandler() {
        this.table = "coins";
    }

    public void setupDatabase() {
        long time = System.currentTimeMillis();
        sql.update("CREATE TABLE IF NOT EXISTS coins(uuid VARCHAR(36), coins INT);");
        Bukkit.getLogger().log(Level.INFO, "Table " + this.table + " successfully created in " + (System.currentTimeMillis() - time) + "ms.");
    }

    public boolean isPlayerExist(final UUID uuid) {
        try (final PreparedStatement statement = sql.prepare("SELECT * FROM " + this.table + " WHERE uuid ='" + uuid.toString() + "';")) {

            final ResultSet resultSet = statement.executeQuery();
            boolean response = false;

            if(resultSet.next()) {
                response = resultSet.getString("uuid") != null;
            }

            return response;
        } catch (Exception e) {
            e.printStackTrace();
        }
        return Boolean.parseBoolean(null);
    }

    public void registerPlayer(final UUID uuid) {
        if(!this.isPlayerExist(uuid)) {
            sql.update("INSERT INTO " + this.table + "(uuid, coins) VALUES ('" + uuid.toString() + "', '0');");
        }
    }

    public void setCoins(final UUID uuid, final int coinAmount) {
        if(this.isPlayerExist(uuid)) {
            sql.update("UPDATE " + this.table + " SET coins ='" + coinAmount + "' WHERE uuid ='" + uuid.toString() + "';");
        }
    }

    public void addCoins(final UUID uuid, final int coinAmount) {
        this.setCoins(uuid, this.getCoins(uuid) + coinAmount);
    }

    public void removeCoins(final UUID uuid, final int coinAmount) {
        this.setCoins(uuid, this.getCoins(uuid) - coinAmount);
    }

    public int getCoins(final UUID uuid) {
        int coins = 0;
        try(final PreparedStatement statement = sql.prepare("SELECT coins FROM " + this.table + " WHERE uuid ='" + uuid.toString() + "';")) {
            final ResultSet resultSet = statement.executeQuery();
            if(resultSet.next()) {
                coins = resultSet.getInt("coins");
            }
        } catch (final SQLException e) {
            e.printStackTrace();
        }
        return coins;
    }

    public String getTable() {
        return table;
    }
}