C＃从AccessDatabase 2010获取某些数据并显示在组合框C＃中 [英] C# Get certain data from AccessDatabase 2010 and display in a combobox C#

问题描述

我曾尝试在MSDN论坛上发布此问题，但是，我没有成功。



我正在尝试为一家企业制作一个C＃Windows Forms应用程序将管理其员工。该应用程序使用Access 2010数据库。编辑员工页面是我遇到的麻烦。我希望员工能够从组合框中选择，格式为：



FirstName LastName，EmployeePosition



数据库名称是EmployeeInformation.accdb

我想从数据库中获取的字段是：



- FirstName

- LastName

- EmployeePosition



组合框的名称是cboSelectEmp





我用来尝试获取这些数据的当前代码是

  private   void  LoadDataToCbo（）
 {
  string  connString =  @  Provider = Microsoft.ACE.OLEDB.12.0; Data Source = EmployeeInformation.accdb; 
  //   string query = @SELECT FirstName from Employees;  
 < span class =code-keyword> string  query = 
  @  SELECT EmpID，LastName +'，'+ FirstName +'（'+ EmployeePosition +'）'作为名称来自员工; 
 OleDbDataAdapter dAdapter =  new  OleDbDataAdapter（query，connString）; 
 DataTable source =  new  DataTable（）; 
 dAdapter.Fill（来源）; 
 cboSelectEmp.DataSource = source; 
  //   cboSelectEmp.ValueMember =FirstName;  
  //   cboSelectEmp.DisplayMember =FirstName;  
 
 cboSelectEmp.DisplayMember =  名称; 
 cboSelectEmp.ValueMember =   EmpID; 
 
} 

解决方案

我使用此代码修复它：

  private   void  LoadDataToCbo（）
 {
  string  connString =  @  Provider = Microsoft.ACE.OLEDB.12.0 ; Data Source = EmployeeInformation.accdb; 
  string  query = 
  @  SELECT（FirstName +''+ LastName +'，'+ EmployeePosition）作为员工的FirstName; 
 OleDbDataAdapter dAdapter =  new  OleDbDataAdapter（query，connString）; 
 DataTable source =  new  DataTable（）; 
 dAdapter.Fill（来源）; 
 cboSelectEmp.DataSource = source; 
 cboSelectEmp.DisplayMember =   FirstName; 
 
 
} 
 

看起来它是ValueMember属性是那个搞砸我的东西。



谢谢大家的帮助

试试这个：

  string  query = 
  @   SELECT EmpID，FirstName as [Name]，LastName，EmployeePosition FROM Employees; 

< blockquote>在备注下的文档中检查此行OleDbDataAdapter构造函数的此重载使用selectConnectionString参数来设置SelectCommand属性。但是，它不会打开连接。您仍然必须明确打开连接。



http://msdn.microsoft.com/en-us/library/2f8y4737(v=vs.110).aspx



我认为这是你的问题





试试这个

  string  query = 
  @  SELECT EmpID，FirstName as [Name]，LastName，EmployeePosition FROM Employees; 
 使用（ var  odb =  new  OleDbConnection（connectionString））
 {
 odb.Open（）; 
  if （odb.State == ConnectionState.Open）
 {
  var  dset =  new  DataTable（）; 
  var  adapter =  new  OleDbDataAdapter（）; 
  var  newCmd =  new  OleDbCommand（query，odb）
 {
 CommandType = CommandType.Text 
}; 
 adapter.SelectCommand = newCmd; 
 adapter.Fill（dset）; 
 odb.Close（）; 
 
} 
} 

I have tried posting this question on MSDN forums, however, i had no success.

I am trying to make a C# Windows Forms Application for a business that will manage its employees. The application uses an Access 2010 Database. The edit Employee page is what I am having trouble with. I want the Employees to be able to be selected from a combobox in the format of:

FirstName LastName, EmployeePosition

The database name is EmployeeInformation.accdb
The fields that I want from the Database are:

- FirstName
- LastName
- EmployeePosition

The name of the Combo Box is cboSelectEmp


The current code i am using to try and get this data is

private void LoadDataToCbo()
        {
            string connString = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=EmployeeInformation.accdb";
           // string query = @"SELECT FirstName from Employees";
            string query =
                @"SELECT EmpID, LastName + ', ' + FirstName + ' (' + EmployeePosition + ')' as Name FROM Employees";
            OleDbDataAdapter dAdapter = new OleDbDataAdapter(query, connString);
            DataTable source = new DataTable();
            dAdapter.Fill(source);
            cboSelectEmp.DataSource = source;
            //cboSelectEmp.ValueMember = "FirstName";
            //cboSelectEmp.DisplayMember = "FirstName";

            cboSelectEmp.DisplayMember = "Name";
            cboSelectEmp.ValueMember = "EmpID";

        }

解决方案

I fixed it using this code:

private void LoadDataToCbo()
       {
           string connString = @"Provider=Microsoft.ACE.OLEDB.12.0;Data Source=EmployeeInformation.accdb";
           string query =
                          @"SELECT (FirstName + ' ' + LastName + ', ' + EmployeePosition) as FirstName from Employees";
           OleDbDataAdapter dAdapter = new OleDbDataAdapter(query, connString);
           DataTable source = new DataTable();
           dAdapter.Fill(source);
           cboSelectEmp.DataSource = source;
           cboSelectEmp.DisplayMember = "FirstName";


       }

it looks like it was the ValueMember property was the thing that was messing with me.

Thanks everyone for all your help

Try This:

string query =
               @"SELECT EmpID, FirstName as [Name], LastName , EmployeePosition   FROM Employees";

Check this line in documentation under remarks This overload of the OleDbDataAdapter constructor uses the selectConnectionString parameter to set the SelectCommand property. However, it does not open the connection. You still must explicitly open the connection.

http://msdn.microsoft.com/en-us/library/2f8y4737(v=vs.110).aspx

I think that is your problem


Try this

string query =
               @"SELECT EmpID, FirstName as [Name], LastName , EmployeePosition   FROM Employees";
using (var odb = new OleDbConnection(connectionString))
                       {
                           odb.Open();
                           if (odb.State == ConnectionState.Open)
                           {
                               var dset = new DataTable();
                               var adapter = new OleDbDataAdapter();
                               var newCmd = new OleDbCommand(query, odb)
                                   {
                                       CommandType =  CommandType.Text
                                   };
                               adapter.SelectCommand = newCmd;
                               adapter.Fill(dset);
                               odb.Close();
                             
                           }
}

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