在android中內建了一個輕量級的資料庫SQLite，今天主要講講資料庫的增刪改查的兩種方式。

方式一：

前提了解：在SQL語句中資料庫增刪改查的語句：

增："insert into info(name,phone) values(?;?)",new Object[]{infobean.name,infobean.phone}
刪："delete from info where name =?;",new Object[]{name}
改："update info set phone =? where name =?;",new Object[]{infobean.phone,infobean.name}
查："select _id,name,phone from info where name =?;",new String[]{name}
 

建立四個類：

Infobean（提供相應的引數）

MainActivity（執行主執行緒）

MySQLiteDataBase extends SQLiteOpenHelper（建立資料庫）

InfoDao（封裝方法）

程式碼如下：

public class Infobean {//定義基本引數

    public String name;
    public String phone;
}

public class InfoDao {//方法封裝

    private MySQLiteDataBase mySQLiteDataBase;
    public InfoDao(Context context){

        mySQLiteDataBase = new MySQLiteDataBase(context);
    }

    public void add(Infobean infobean) {
        SQLiteDatabase db = mySQLiteDataBase.getWritableDatabase();
        db.execSQL("insert into info(name,phone) values(?;?)",new Object[]{infobean.name,infobean.phone});
        db.close();
    }

    public void del(String name) {
        SQLiteDatabase db = mySQLiteDataBase.getReadableDatabase();
        db.execSQL("delete from info where name =?;",new Object[]{name});
        db.close();
    }

    public void update(Infobean infobean) {
        SQLiteDatabase db = mySQLiteDataBase.getReadableDatabase();
        db.execSQL("update info set phone =? where name =?;",new Object[]{infobean.phone,infobean.name});
//        db.execSQL("update info set phone=? where name=?;", new Object[]{infobean.phone,infobean.name});
        db.close();
    }

    public void query(String name) {
        SQLiteDatabase db = mySQLiteDataBase.getReadableDatabase();
        Cursor cursor = db.rawQuery("select _id,name,phone from info where name =?;",new String[]{name});
        if(cursor != null && cursor.getCount()>0){
            while (cursor.moveToNext()){
                int id = cursor.getInt(0);
                String mName = cursor.getString(1);
                String mPhone = cursor.getString(2);
                Log.d("msg",id + " "+mName + " " + mPhone);
            }
            cursor.close();
        }
        db.close();
    }

}
 

public class MySQLiteDataBase extends SQLiteOpenHelper {//建立資料庫

    public MySQLiteDataBase(Context context) {
        super(context,"info.db",null,1);
    }

    @Override
    public void onCreate(SQLiteDatabase sqLiteDatabase) {
        sqLiteDatabase.execSQL("create table info(_id integer primary key autoincrement," +
                "name varchar(20),phone varchar(20))");
    }

    @Override
    public void onUpgrade(SQLiteDatabase sqLiteDatabase, int i, int i1) {

    }
}
 

public class MainActivity extends AppCompatActivity implements View.OnClickListener {//需要執行的主函式

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

        MySQLiteDataBase mySQLiteDataBase = new MySQLiteDataBase(this);
        SQLiteDatabase db = mySQLiteDataBase.getReadableDatabase();

        findViewById(R.id.bt_add).setOnClickListener(this);
        findViewById(R.id.bt_del).setOnClickListener(this);;
        findViewById(R.id.bt_update).setOnClickListener(this);;
        findViewById(R.id.bt_query).setOnClickListener(this);;
    }

    @Override
    public void onClick(View view) {
        InfoDao infoDao = new InfoDao(this);
        switch (view.getId()){

            case R.id.bt_add:
                Infobean infobean = new Infobean();
                infobean.name = "張三";
                infobean.phone = "119";
                infoDao.add(infobean);

                Infobean infobean1 = new Infobean();
                infobean1.name = "李三";
                infobean1.phone = "110";
                infoDao.add(infobean1);
                break;

            case R.id.bt_del:
                infoDao.del("李三");
                break;

            case R.id.bt_update:
                Infobean bean = new Infobean();
                bean.name = "張三";
                bean.phone = "120";
                infoDao.update(bean);
                break;

            case R.id.bt_query:
                infoDao.query("張三");
                infoDao.query("李三");
                break;
        }
    }
}

方式二：

 方式一中相應操作的SQL語句都需要自己去寫，比較麻煩，也比較容易出錯，對此，android提供了相應封裝好的類來執行相應的操作。

public boolean add(Infobean infobean) {//增加的方法
        SQLiteDatabase db = mySQLiteDataBase.getWritableDatabase();

//       方法二（有返回值）：
        ContentValues contentValues = new ContentValues();
        contentValues.put("name",infobean.name);
        contentValues.put("phone",infobean.phone);
        long i = db.insert("info",null,contentValues);
        db.close();
        if(i == -1){
            return false;
        }
        return true;
    }

public void del(String name, Context context) {//刪除的方法
        SQLiteDatabase db = mySQLiteDataBase.getReadableDatabase();

       int i =  db.delete("info","name = ? ",new String[]{name});
       Toast.makeText(context,"刪除了"+ i+ "行",Toast.LENGTH_SHORT).show();
        db.close();
    }

public void update(Infobean infobean, Context context) {//修改的方法
        SQLiteDatabase db = mySQLiteDataBase.getReadableDatabase();
        ContentValues contentValues = new ContentValues();
        contentValues.put("phone",infobean.phone);
        int resule = db.update("info",contentValues,"name = ?",new String[]{infobean.name});
        Toast.makeText(context,"修改了"+ resule + "行",Toast.LENGTH_SHORT).show();
        db.close();
    }

public void query(String name) {
        SQLiteDatabase db = mySQLiteDataBase.getReadableDatabase();
        Cursor cursor = db.query("info",new String[]{"_id","name","phone"},"name = ?",new String[]{name},null,null,"_id desc");
        if(cursor != null && cursor.getCount()>0){
            while (cursor.moveToNext()){
                int id = cursor.getInt(0);
                String mName = cursor.getString(1);
                String mPhone = cursor.getString(2);
                Log.d("msg",id + " "+mName + " " + mPhone);
            }
            cursor.close();
        }
        db.close();
    }