新版android studio如何连接数据库

在新版Android Studio中连接SQLite数据库的步骤如下：

1.在项目的build.gradle文件中添加以下依赖项：

dependencies {
    implementation 'androidx.sqlite:sqlite:2.1.0'
}

2.在Java代码中创建SQLiteOpenHelper类，该类将帮助您创建和管理数据库。以下是一个示例：

public class MyDatabaseHelper extends SQLiteOpenHelper {
    private static final String DATABASE_NAME = "mydatabase.db";
    private static final int DATABASE_VERSION = 1;

    public MyDatabaseHelper(Context context) {
        super(context, DATABASE_NAME, null, DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {
        // 创建表格
        db.execSQL("CREATE TABLE mytable (id INTEGER PRIMARY KEY AUTOINCREMENT, name TEXT, age INTEGER)");
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // 升级数据库
        db.execSQL("DROP TABLE IF EXISTS mytable");
        onCreate(db);
    }
}

3.在您的Activity或Fragment中，创建MyDatabaseHelper对象并获取可写数据库实例：

MyDatabaseHelper dbHelper = new MyDatabaseHelper(getContext());
SQLiteDatabase db = dbHelper.getWritableDatabase();

4.现在您可以使用SQLiteDatabase对象执行SQL查询和更新。以下是一个示例：

// 插入数据
ContentValues values = new ContentValues();
values.put("name", "John");
values.put("age", 30);
db.insert("mytable", null, values);

// 查询数据
Cursor cursor = db.query("mytable", null, null, null, null, null, null);
while (cursor.moveToNext()) {
    int id = cursor.getInt(cursor.getColumnIndex("id"));
    String name = cursor.getString(cursor.getColumnIndex("name"));
    int age = cursor.getInt(cursor.getColumnIndex("age"));
    Log.d("MyApp", "id: " + id + ", name: " + name + ", age: " + age);
}

// 更新数据
ContentValues values = new ContentValues();
values.put("age", 31);
db.update("mytable", values, "name = ?", new String[]{"John"});

// 删除数据
db.delete("mytable", "name = ?", new String[]{"John"});