public void insertDB(View view)

    {

        MyDBHelper mydbh=new MyDBHelper(this,"amydb.db",1);

        SQLiteDatabase sqldb=mydbh.getReadableDatabase();

        ContentValues contentvalues=new ContentValues();

        text1=(EditText)findViewById(R.id.tv_text1);

        text2=(EditText)findViewById(R.id.tv_text2);

        text3=(EditText)findViewById(R.id.tv_text3);

        text4=(EditText)findViewById(R.id.tv_text4);

        contentvalues.put("name",text1.getText().toString());

        contentvalues.put("dateandtime",text2.getText().toString());

        contentvalues.put("address",text4.getText().toString());

        contentvalues.put("wendu",text3.getText().toString());

        long flag=sqldb.insert("personwendu",null,contentvalues);

        Toast.makeText(this,"数据加入成功"+flag,Toast.LENGTH_LONG).show();

    }

public void deleteDate(View view)

    {

        MyDBHelper mydbh=new MyDBHelper(this,"mydb.db",1);

        SQLiteDatabase sqldb=mydbh.getReadableDatabase();

        int flag=sqldb.delete("person","id=1",null);

        Toast.makeText(this,"已有"+flag+"条数据删除",Toast.LENGTH_LONG).show();

    }

public void updateData(View view)

    {

        MyDBHelper mydbh=new MyDBHelper(this,"mydb.db",1);

        SQLiteDatabase sqldb=mydbh.getReadableDatabase();

        ContentValues contentvalues=new ContentValues();

        contentvalues.put("name","明明");

        contentvalues.put("age","12");

        int flag=sqldb.update("person",contentvalues,"name=?",new String[]{"李明"});

        Toast.makeText(this,"已有"+flag+"条数据修改",Toast.LENGTH_LONG).show();

    }

 public void queryData(View view)

    {

        MyDBHelper mydbh=new MyDBHelper(this,"amydb.db",1);

        SQLiteDatabase sqldb=mydbh.getReadableDatabase();

        Cursor cursor=sqldb.rawQuery("select * from personwendu",null);

        String str="";

        if(cursor.moveToFirst())

        {

            do{

                String name=cursor.getString(cursor.getColumnIndex("name"));

                String dateandtime=cursor.getString(cursor.getColumnIndex("dateandtime"));

                String address=cursor.getString(cursor.getColumnIndex("address"));

                String wendu=cursor.getString(cursor.getColumnIndex("wendu"));

                str=str+name+"|"+dateandtime+"|"+wendu+"\n"+address+"\n";

            }while(cursor.moveToNext());

        }

        AlertDialog.Builder builder=new AlertDialog.Builder(this);

        builder.setTitle("历史记录").setIcon(R.mipmap.ic_launcher).setMessage(str)

                .setPositiveButton("ok", new DialogInterface.OnClickListener() {

                    @Override

                    public void onClick(DialogInterface dialog, int which) {

                    }

                });

        AlertDialog ad=builder.create();

        ad.show();

    }