android studio sqlite操作代码片段

SQLiteDatabase db;
Cursor cur;

SimpleCursorAdapter adapter;

// 打开或创建数据库
db = openOrCreateDatabase(DB_NAME,  Context.MODE_PRIVATE, null);

// 创建数据表
String createTable="CREATE TABLE IF NOT EXISTS " + TB_NAME +
        "(_id INTEGER PRIMARY KEY AUTOINCREMENT, " + //索引字段
        "name VARCHAR(32), " +
        "phone VARCHAR(16), " +
        "email VARCHAR(64))";
db.execSQL(createTable);

cur=db.rawQuery("SELECT * FROM "+ TB_NAME, null);  // 查询数据

// 若查询结果是空的则写入 2 项测试数据
if(cur.getCount()==0){
    addData("旗标公司","02-23963257","service@flag.com.tw");
    addData("旗讯公司","02-23214335","service@pcdiy.com.tw");
}

adapter=new SimpleCursorAdapter(this,
        R.layout.item, cur,
        FROM,
        new int[] {R.id.name,R.id.phone,R.id.email}, 0);

lv=(ListView)findViewById(R.id.lv);
lv.setAdapter(adapter);           // 设置 Adapter
lv.setOnItemClickListener(this); // 设置单击事件的监听器
requery(); // 调用自定义方法, 重新查询及设置按钮状态

}

private void addData(String name, String phone, String email) {
    ContentValues cv=new ContentValues(3); // 创建含 3 个字段的 ContentValues对象
    cv.put(FROM[0], name);
    cv.put(FROM[1], phone);
    cv.put(FROM[2], email);

    db.insert(TB_NAME, null, cv);  // 新增1个记录
}

private void update(String name, String phone, String email, int id) {
    ContentValues cv=new ContentValues(3);
    cv.put(FROM[0], name);
    cv.put(FROM[1], phone);
    cv.put(FROM[2], email);

    db.update(TB_NAME, cv, "_id="+id, null);   // 更新 id 所指的字段
}

public void call(View v){  // 打电话
    String uri="tel:" + cur.getString(
            cur.getColumnIndex(FROM[1]));
    Intent it = new Intent(Intent.ACTION_VIEW, Uri.parse(uri));
    startActivity(it);
}

public void mail(View v){  // 发送电子邮件
    String uri="mailto:"+cur.getString(
            cur.getColumnIndex(FROM[2]));
    Intent it = new Intent(Intent.ACTION_SENDTO, Uri.parse(uri));
    startActivity(it);
}