小编Sco*_*ion的帖子

我是来自 DataTable 的人口 DataGridView，但收到以下错误：

DataGridView 控件的至少一列没有单元格模板

private void PopulateGridView(DataTable dt)
        {

            if (dt != null)
            {
                dataGridView1.Columns.Clear();
                dataGridView1.DataSource = null;

                foreach (DataColumn col in dt.Columns)
                {
                    //Declare the bound field and allocate memory for the bound field.
                    DataGridViewColumn datacolumn = new DataGridViewColumn();

                    //Initalize the DataField value.
                    datacolumn.DataPropertyName = col.ColumnName;

                    datacolumn.Name = col.ColumnName;

                    //Initialize the HeaderText field value.
                    datacolumn.HeaderText = col.ColumnName;


                    //Add the newly created bound field to the GridView.
                    this.dataGridView1.Columns.Add(datacolumn); // ** Error **
            }

                //Initialize the DataSource
                this.dataGridView1.DataSource = …

您好我试图从方法返回DataReader但它返回一个关闭的DbDataReader对象.任何想法来解决这个问题.我愿意接受任何使代码更好的建议.

谢谢

更新 我不想让数据库连接保持打开状态.是否有任何方法可以在关闭连接后返回打开的DataReader.

internal DbDataReader ExecuteReader(SqlCommand command, CommandBehavior behavior, string connectionString)
  {
    DbDataReader dataReader = null;
    try
    {
      SqlConnection connection = GetConnection(connectionString);
      Open(connection);
      command.Connection = connection;
      command.CommandTimeout = 60;
      dataReader = command.ExecuteReader(behavior);
      Close(connection);
    }
    catch
    {
    }
    return dataReader;
}

我正在编写一个查询来获取PersonID的地址.以下查询对我有用,但它只返回两个地址.我想用单个查询处理'n'个地址.有没有办法做到这一点？

非常感谢

SELECT 
  PersonID, PersonName
  [Address1], [Address2]
FROM
  (
  SELECT 
    P.PersonID, 
    P.PersonName, 
    (ROW_NUMBER() OVER(PARTITION BY P.PersonID ORDER BY A.AddressID)) RowID
    FROM tblPerson
    INNER JOIN tblAddress AS A ON A.PersonID = P.PersonID
  ) AS AddressTable
PIVOT
  (
    MAX(AddressID)
    FOR RowID IN ([Address1], [Address2])
  ) AS PivotTable;

我正在学习大学数据库,并负责找到大学课程的最低平均考试成绩.我已经提出了两个解决方案,但我希望你们这里的专家可以帮助我:

什么是最好/最有效的解决方案？

解决方案1:

SELECT courses.name , MIN(avg_grade)
FROM (SELECT courseCode, AVG(grade) as avg_grade
      FROM exams
      GROUP BY courseCode) avg_grades, courses
WHERE courses.code = avg_grades.courseCode

解决方案2:

SELECT name, min(avg_grade)
FROM (SELECT courses.name, AVG(grade) as avg_grade
      FROM courses
      LEFT JOIN exams on exams.courseCode = courses.code
      GROUP BY courseCode) mytable

而且我一直在考虑JOIN或LEFT JOIN在这里使用是否正确？

我有一个返回bool值的方法.我想通过执行该方法Thread.

Thread t1 = new Thread(new ThreadStart(doThis));

你能否建议一种获得返回值的方法？

我试图在视图上显示错误消息.能否建议我采取正确的方法来做到这一点.我正在考虑动态添加数据注释,但找不到任何解决方案.

谢谢

[HttpPost]
public ActionResult AddBook(BooksModel booksModel)
{           
    try
    {
        booksModel.Account = _bookRepository.BookDetails(booksModel.Title,booksModel.RefCode, booksModel.DontHaveRefCode);
    }
    catch (FaultException faultException)
    {
        switch (faultException.Code.Name)
        {
            case "exc1":
            // Show Error Message Here
            return View("AddBook", booksModel);
            default:
            break;
        }
    }
    return View("ConfirmBook", booksModel);
}

我有一个表Main1有21条记录,临时表 @recordsToDel有20条记录.20两个表中的行相同,但以下选择查询不返回丢失的记录,删除也不会删除它.两个表都有类似的列.

有什么建议吗？

SELECT * FROM dbo.Main1
WHERE NOT EXISTS
(
    SELECT * FROM @recordsToDel
);

DELETE FROM dbo.Main1
WHERE NOT EXISTS
(
    SELECT * FROM @recordsToDel
);

非常感谢

嗨,我在CRM 2011中创建新帐户时获得以下错误.请提出任何建议.

谢谢

未处理的异常:

System.ServiceModel.FaultException`1[[Microsoft.Xrm.Sdk.OrganizationServiceFault,  Microsoft.Xrm.Sdk, Version=5.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35]]:  Object reference not set to an instance of an object.Detail:
<OrganizationServiceFault xmlns:i="http://www.w3.org/2001/XMLSchema-instance"  xmlns="http://schemas.microsoft.com/xrm/2011/Contracts">
  <ErrorCode>-2147220891</ErrorCode>
  <ErrorDetails xmlns:d2p1="http://schemas.datacontract.org/2004/07/System.Collections.Generic">
    <KeyValuePairOfstringanyType>
      <d2p1:key>OperationStatus</d2p1:key>
      <d2p1:value xmlns:d4p1="http://www.w3.org/2001/XMLSchema" i:type="d4p1:string">0</d2p1:value>
    </KeyValuePairOfstringanyType>
  </ErrorDetails>
  <Message>Object reference not set to an instance of an object.</Message>
  <Timestamp>2012-04-02T11:03:57.7288333Z</Timestamp>
  <InnerFault i:nil="true" />
  <TraceText>[AutoNumberGenerator: AutoNumberGenerator.AutoNumberGenerator] [9202e5b5-d848-e111-8920-0050569b0118: AutoNumberGenerator.AutoNumberGenerator: Create of account]    
</TraceText>
</OrganizationServiceFault>

我正在尝试使用Select语言功能开发MVC3(razor)应用程序.

使用以下视图作为_SelectCulture上的部分视图_Layout.cshtml

<text>
   @Html.ActionLink("English", "SetCulture", new { controller = "Culture", culture = "en-GB" })  
   | 
   @Html.ActionLink("Welsh", "SetCulture", new { controller = "Culture", culture = "cy-GB" })
</text>
<div>
    @System.Threading.Thread.CurrentThread.CurrentUICulture.ToString()
</div>

CultureController

public ActionResult SetCulture(string culture)
        {
        System.Globalization.CultureInfo ci = new     System.Globalization.CultureInfo(culture);

            System.Threading.Thread.CurrentThread.CurrentCulture = ci;
            System.Threading.Thread.CurrentThread.CurrentUICulture = ci;

            return RedirectToAction("Index", "Home");
        }

但它仍然没有改变语言.

请帮忙.

谢谢