Question

我正在编写linq查询以从表中获取一些细节。对于每个"notVerified"，我希望clientID计算ID clientId clientName empID docStatus 1 IN1001 Infy 100 Verified 2 IN1001 Infy 101 notVerified 3 IN1001 Infy 102 notVerified。

我的表格结构如下

clientID    clientName    Count
IN1001      Infy          2

查询后我想要下面表格中的数据

var noofRecords = (from c in db.ts_upld_doc
                   group c by c.upld_docid into grouping
                   select new
                   {
                       key = grouping.Key,
                       Count = grouping.Count()
                   });
return noofRecords.Count();

这是我在下面尝试的。我能够得到数，但我应该在下面的查询中放置条件。

package com.example.dekrinssoft.contactsbackup;
import android.app.ProgressDialog;
import android.content.DialogInterface;
import android.content.Intent;
import android.content.res.AssetFileDescriptor;
import android.database.Cursor;
import android.net.Uri;
import android.os.AsyncTask;
import android.os.Environment;
import android.provider.ContactsContract;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import android.view.View;
import android.webkit.MimeTypeMap;
import android.widget.Button;
import android.widget.Toast;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {
Button backup, restore;
String vfile;
FileOutputStream mFileOutputStream = null;
Cursor cursor;
ArrayList<String> vCard;
File f;
String storage_path;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    backup = (Button) findViewById(R.id.btnbkp);
    restore = (Button) findViewById(R.id.btnres);

    vfile = "contacts.vcf";
    storage_path = Environment.getExternalStorageDirectory().toString() + "/" + vfile;
    f = new File(storage_path);


    backup.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

            new LongOperation().execute("");

        }
    });
    restore.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            final Intent intent = new Intent();

            final MimeTypeMap mime = MimeTypeMap.getSingleton();
            String tmptype = mime.getMimeTypeFromExtension("vcf");
            final File file = new File(Environment.getExternalStorageDirectory().toString() + "/contacts.vcf");

            intent.setDataAndType(Uri.fromFile(file), tmptype);
            startActivity(intent);
        }
    });

}

private class LongOperation extends AsyncTask<String, Void, String> {

    ProgressDialog progress;

    @Override
    protected void onPreExecute() {
        progress = new ProgressDialog(MainActivity.this);
        progress.setMessage("Loading.... ");
        progress.setProgressStyle(ProgressDialog.STYLE_SPINNER);
        progress.setIndeterminate(true);
        progress.setProgress(0);
        progress.show();
    }

    @Override
    protected String doInBackground(String... params) {
        try {
            if (!f.exists())
                f.createNewFile();
            mFileOutputStream = new FileOutputStream(storage_path, false);
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        getVcardString();
        return "Executed";
    }

    @Override
    protected void onPostExecute(String result) {
        Toast.makeText(MainActivity.this,  " Succesfully backed up", Toast.LENGTH_LONG).show();
        progress.dismiss();
    }

}

private void getVcardString() {
    vCard = new ArrayList<String>();
    cursor = getContentResolver().query(ContactsContract.CommonDataKinds.Phone.CONTENT_URI, null, null, null, null);
    if (cursor != null && cursor.getCount() > 0) {
        cursor.moveToFirst();
        for (int i = 0; i < cursor.getCount(); i++) {

            get(cursor);
            Log.d("TAG", "Contact " + (i + 1) + "VcF String is" + vCard.get(i));
            cursor.moveToNext();
        }

    } else {
        Log.d("TAG", "No Contacts in Your Phone");
    }
    try {
        mFileOutputStream.close();
    } catch (IOException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

}

public void get(Cursor cursor) {
    //cursor.moveToFirst();
    String lookupKey = cursor.getString(cursor.getColumnIndex(ContactsContract.Contacts.LOOKUP_KEY));
    Uri uri = Uri.withAppendedPath(ContactsContract.Contacts.CONTENT_VCARD_URI, lookupKey);
    AssetFileDescriptor fd;
    try {
        fd = this.getContentResolver().openAssetFileDescriptor(uri, "r");
        FileInputStream fis = fd.createInputStream();
        byte[] buf = new byte[(int) fd.getDeclaredLength()];
        fis.read(buf);
        String vcardstring = new String(buf);
        vCard.add(vcardstring);

        mFileOutputStream.write(vcardstring.toString().getBytes());

    } catch (Exception e1) {
        // TODO Auto-generated catch block
        e1.printStackTrace();
    }
}


@Override
public boolean onCreateOptionsMenu(Menu menu) {
    // Inflate the menu; this adds items to the action bar if it is present.
    getMenuInflater().inflate(R.menu.menu_main, menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    // Handle action bar item clicks here. The action bar will
    // automatically handle clicks on the Home/Up button, so long
    // as you specify a parent activity in AndroidManifest.xml.
    int id = item.getItemId();

    //noinspection SimplifiableIfStatement
    if (id == R.id.action_settings) {
        return true;
    }

    return super.onOptionsItemSelected(item);
}
}

提前谢谢。

Answer 1

您可能会在分组之前放置where子句的内容（为什么要对要过滤的这些项进行分组）。然后，如果您想要按照指定的方式输出，最简单的方法是按clientID和clientName分组。

同样在您的上述查询中，您按upld_docid（ID）字段进行分组 - 这是您数据中的唯一字段 - 意味着您的所有群组的大小均为1 - 就像您没有＆＃39; t group。

见下面的查询，应该做你想做的事：

var noofRecords = (from c in db.ts_upld_doc
                   where c.docStatus == "notVerified"
                   group c by new { c.clientID, c.clientName }  into grouping
                   select new
                   {
                        ClientId = grouping.Key.clientID,
                        ClientName = grouping.Key.clientName,
                        Count = grouping.Count()
                   }).ToList();

Answer 2

您可以将地点放在多个地方，一个选项：

var noofRecords = (from c in db.ts_upld_doc
                   where c.docStatus == "notVerified"
                   group c by c.upld_docid into grouping
                   select new
                   {
                        key = grouping.Key,
                        Count = grouping.Count()
                   });

return noofRecords.Count();

要意识到!!您返回的是记录数，而不是您设置为grouping.Count()

的财产计数

要获得预期结果，您应该执行以下操作：

var noofRecords = (from c in db.ts_upld_doc
                   where c.docStatus == "notVerified"
                   group c by new { c.clientId , c.clientName } into grouping
                   select new
                   {
                      ClientId  = grouping.Key.clientId,
                      ClientName = grouping.Key.clientName,
                      Count = grouping.Count()
                   });

return noofRecords.ToList();

Linq group通过查询与mvc4中的count和其他字段

2 个答案: