使用Android中的SQL从列表中删除特定用户

// 继承SQLiteOpenHelper类来创建数据库和表
public class MyDatabaseHelper extends SQLiteOpenHelper {
    private static final String DATABASE_NAME = "user.db";
    private static final int DATABASE_VERSION = 1;
    private static final String TABLE_NAME = "user";
    private static final String COLUMN_USERNAME = "username";
    private static final String COLUMN_PASSWORD = "password";
    // 其他字段...

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

    @Override
    public void onCreate(SQLiteDatabase db) {
        String createTableQuery = "CREATE TABLE " + TABLE_NAME + "(" +
                COLUMN_USERNAME + " TEXT PRIMARY KEY, " +
                COLUMN_PASSWORD + " TEXT, " +
                // 其他字段...
                ")";
        db.execSQL(createTableQuery);
    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
        // 如果数据库版本更新，可以在这里处理
    }
}

// 在应用程序中使用数据库
public class MainActivity extends AppCompatActivity {
    private SQLiteDatabase mDatabase;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        MyDatabaseHelper dbHelper = new MyDatabaseHelper(this);
        mDatabase = dbHelper.getWritableDatabase();

        // 调用删除用户方法
        deleteUser("John");

        // 关闭数据库
        mDatabase.close();
    }

    private void deleteUser(String username) {
        String deleteQuery = "DELETE FROM " + MyDatabaseHelper.TABLE_NAME +
                " WHERE " + MyDatabaseHelper.COLUMN_USERNAME + "='" + username + "'";
        mDatabase.execSQL(deleteQuery);
    }
}