sqldelight:如何保证`create`只被调用一次

public class DatabaseHelper {
    private static volatile DatabaseHelper instance;

    private DatabaseHelper() {
        // 私有构造函数
    }

    public static DatabaseHelper getInstance() {
        if (instance == null) {
            synchronized (DatabaseHelper.class) {
                if (instance == null) {
                    instance = new DatabaseHelper();
                    instance.create();
                }
            }
        }
        return instance;
    }

    private void create() {
        // 创建数据库表的逻辑
    }
}

public class DatabaseHelper {
    private static boolean isCreated = false;

    public void create() {
        if (!isCreated) {
            // 创建数据库表的逻辑
            isCreated = true;
        }
    }
}

public class DatabaseHelper extends SQLiteOpenHelper {
    private static final int DATABASE_VERSION = 1000;

    public DatabaseHelper(Context context) {
        super(context, "mydatabase.db", null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        // 创建数据库表的逻辑
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // 数据库升级逻辑
    }
}