Question

我有一个带有一些重复记录的mysql表，有一列EOF。如果所有数据都正确，那么将为所有列插入ok。如果某些数据错误，则会为这些错误的数据记录插入错误。如果没有错误，则相关列中将显示ok。

但如果有错误，那么我想通过使用group by显示错误。我该如何为此编写查询？

样本表

Error_code

我使用group by

使用以下查询

voucherid ean error_code
123456    234 OK
123456    435 OK
123456    345 Ok

此查询将返回此数据：

select voucherid, error_code 
from voucher_info 
group by voucher id

但如果我在数据中有错误代码，那么表格将如下所示

voucherid error_code
123456     ok

现在我想将error_code值显示为如下所示的错误。

voucherid ean error_code
123456    234 OK
123456    435 Error
123456    345 Ok

如何通过使用group by来做到这一点？任何帮助将不胜感激。

Answer 1

我不确定你是否有2张桌子或只有一张桌子。如果你有一张桌子和只想知道是否有错误，你可以这样做：

public class MainActivity extends AppCompatActivity {

private final String TAG = "MainActivity";
public static final MediaType JSON = MediaType.parse("application/json; charset=utf-8");
public static final String BASE_URL = "http://...";

private ArrayList<Userlist> userList;
private RecyclerView recyclerView;
private RecyclerViewAdapter adapter;
private RecyclerView.LayoutManager layoutManager;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main_layout);
    recyclerView = (RecyclerView) findViewById(R.id.rv_user);
    recyclerView.setHasFixedSize(true);
    //LayoutManager
    layoutManager = new LinearLayoutManager(this);
    recyclerView.setLayoutManager(layoutManager);
    recyclerView.setAdapter(adapter);
    //Adapter
    adapter = new RecyclerViewAdapter(userList);
    recyclerView.setLayoutManager(layoutManager);
    ButterKnife.bind(this);
    getAllUsers();
}

@Override
protected void onPostResume() {
    super.onPostResume();
    recyclerView.setAdapter(adapter);
}


private void getAllUsers() {

    OkHttpClient client = new OkHttpClient();

    Request request = new Request.Builder()
            .url(BASE_URL + "user")
            .build();

    client.newCall(request).enqueue(new Callback() {
        @Override
        public void onFailure(Call call, IOException e) {
            e.printStackTrace();
        }

        @Override
        public void onResponse(Call call, Response response) throws IOException {
            String responseStr = response.body().string();
            GsonBuilder gsonBuilder = new GsonBuilder();
            Gson gson = gsonBuilder.create();
            List<Userlist> userList = new ArrayList<>();
            userList = Arrays.asList(gson.fromJson(responseStr, Userlist.class));
            System.out.print(responseStr);
            response.body().close();
            adapter.notifyDataSetChanged();
        }
    });
}}

<强>样品

SELECT
    vi.voucherid
    , GROUP_CONCAT(ean) eans
    , IF( COUNT(*) - SUM(IF(error_code = 'ERROR' OR @err = 'ERROR' , 0 , 1)) = 0 , 'OK', 'ERROR') error_code
FROM voucher_info vi
CROSS JOIN ( SELECT @err:='') AS initial
GROUP BY voucherid;

使用Group by Mysql显示所需的结果

1 个答案: