删除表中数据的两种方法（delete删）

Posted 2020-09-04 懂你在爱我

1.通过点击按钮来执行删除表中数据。（数据库和表的创建不在详细介绍，请自动阅读数据库和表的创建）

第一种方法：直接使用SQL来操作数据库，调用execSQL(sql)语句

public class MainActivity extends AppCompatActivity {
    private Button mDeleteButton;
    private mysqliteHelper mMySqliteHelper;
    private SQLiteDatabase db;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mMySqliteHelper = DbManger.getIntance(MainActivity.this);
        mDeleteButton = (Button) findViewById(R.id.delete_btn);
        //点击按钮删除数据
        mDeleteButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                db = mMySqliteHelper.getWritableDatabase();
                String sql = "delete from "+Constant.TABLE_NAME+" where "+Constant.ID+" = 2 ";
                db.execSQL(sql);
                db.close();
            }
        });
    }
}

第二种方法：使用android API封装好的删除数据的操作

public class MainActivity extends AppCompatActivity {
    private Button mDeleteButton;
    private MySqliteHelper mMySqliteHelper;
    private SQLiteDatabase db;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        mMySqliteHelper = DbManger.getIntance(MainActivity.this);
        mDeleteButton = (Button) findViewById(R.id.delete_btn);
        //点击按钮删除数据
        mDeleteButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                db = mMySqliteHelper.getWritableDatabase();
                db.delete(Constant.TABLE_NAME,Constant.ID+" = ?",new String[]{"3"});
                db.close();
            }
        });
    }
}