如何使用C#访问中的过滤器选择特定字段 [英] how to select specific field using a filter from access in C#

问题描述

在C#和Windows窗体中，

我有一个这样的数据库:

这就是我使用类将其数据放入datagridview的方式:

    class DBConnection
{
    public static void GetList(Form2 frm2)
    {
        string DBPath = Application.StartupPath;
        OleDbConnection Connection = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source="+DBPath+@"\DataBase\SampleFeeds.accdb");
        OleDbDataAdapter DataA = new OleDbDataAdapter("Select * from FeedLibrary", Connection);
        DataTable Dtable = new DataTable();
        DataA.Fill(Dtable);
        frm2.SelectedFeeddataGridView.DataSource = Dtable;
    }

}

这是我的表单加载:

private void Form2_Load(object sender, EventArgs e)
    {
        DBConnection.GetList(this);
    }

到目前为止，一切正常.

现在我有一个问题:

例如，我有一个列表框FeedSelectListBox， 我想当用户单击按钮GrassLegumeForagebtn我的FeedSelectListBox时，只用草/豆类饲料类别中的所有饲料名称填充.

我应该怎么做?

在达米尔基的帮助下，我的问题解决了

//-----------------

但是现在我有另一个问题: 我想当用户从列表框中选择一个提要时，将其所有来自数据库的数据(例如名称，编号，提要类型和",,")放入数据网格视图中.

我在SelectFeedbtn上使用了此代码，但是它不起作用:

private void SelectFeedbtn_Click(object sender, EventArgs e)
    {
        string StrCon = System.Configuration.ConfigurationManager.ConnectionStrings["FeedLibraryConnectionString"].ConnectionString;
        OleDbConnection Connection = new OleDbConnection(StrCon);
        string FeedSelectedID = FeedSelectListBox.SelectedValue.ToString();
        OleDbDataAdapter DataA = new OleDbDataAdapter("Select * from FeedLibrary where ID = 'FeedSelectedID'" , Connection);
        DataTable DTable = new DataTable();
        DataA.Fill(DTable);
        SelectedFeeddataGridView.DataSource = DTable;
    }

FeedSelectListBox的ValueMember属性是ID，但错误是:

System.Data.dll中发生了类型为'System.Data.OleDb.OleDbException'的未处理异常.

我什至使用此查询，但仍然无法正常工作:

OleDbDataAdapter DataA = new OleDbDataAdapter("Select * from FeedLibrary where ID =" FeedSelectListBox.SelectedValue , Connection);

首先，您最先设置FeedSelectListBox的DisplayMember和ValueMember属性，并在点击事件上使用此代码. 您可以将此代码放在GrassLegumeForagebtn click事件上.

string DBPath = Application.StartupPath;
        OleDbConnection Connection = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source="+DBPath+@"\DataBase\SampleFeeds.accdb");
        OleDbDataAdapter DataA = new OleDbDataAdapter("Select * from FeedLibrary where category='Grass / Legume'", Connection);
        DataTable Dtable = new DataTable();
        DataA.Fill(Dtable);
        frm2.FeedSelectListBox .DataSource = Dtable;

in C# and windows Form,

I have a database like this:

and this is how I using a class put it's data into a datagridview:

    class DBConnection
{
    public static void GetList(Form2 frm2)
    {
        string DBPath = Application.StartupPath;
        OleDbConnection Connection = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source="+DBPath+@"\DataBase\SampleFeeds.accdb");
        OleDbDataAdapter DataA = new OleDbDataAdapter("Select * from FeedLibrary", Connection);
        DataTable Dtable = new DataTable();
        DataA.Fill(Dtable);
        frm2.SelectedFeeddataGridView.DataSource = Dtable;
    }

}

and this is my form load:

private void Form2_Load(object sender, EventArgs e)
    {
        DBConnection.GetList(this);
    }

So far everything is ok.

now I have a question:

for example I have a list box FeedSelectListBox, I want to when user click on a button GrassLegumeForagebtn my FeedSelectListBox fill with only all of Feed Names that are in the category of Grass / Legume Forage.

how should I do that ?

with help of Damirchi My problem solved

//-----------------

But now I have another question: I want to when user select a feed from list box all of it's data from data base (like name, number, feed type and ,,,) put in a data grid view.

I used this code on my SelectFeedbtn but it doesn't work :

private void SelectFeedbtn_Click(object sender, EventArgs e)
    {
        string StrCon = System.Configuration.ConfigurationManager.ConnectionStrings["FeedLibraryConnectionString"].ConnectionString;
        OleDbConnection Connection = new OleDbConnection(StrCon);
        string FeedSelectedID = FeedSelectListBox.SelectedValue.ToString();
        OleDbDataAdapter DataA = new OleDbDataAdapter("Select * from FeedLibrary where ID = 'FeedSelectedID'" , Connection);
        DataTable DTable = new DataTable();
        DataA.Fill(DTable);
        SelectedFeeddataGridView.DataSource = DTable;
    }

And ValueMember property of FeedSelectListBox is ID but the error is :

An unhandled exception of type 'System.Data.OleDb.OleDbException' occurred in System.Data.dll.

I even use this query but it still doesn't work:

OleDbDataAdapter DataA = new OleDbDataAdapter("Select * from FeedLibrary where ID =" FeedSelectListBox.SelectedValue , Connection);

解决方案

at first you most set the DisplayMember and ValueMember properties of FeedSelectListBox and use this code on click event. you can put this code on GrassLegumeForagebtn click event.

string DBPath = Application.StartupPath;
        OleDbConnection Connection = new OleDbConnection(@"Provider=Microsoft.ACE.OLEDB.12.0;Data Source="+DBPath+@"\DataBase\SampleFeeds.accdb");
        OleDbDataAdapter DataA = new OleDbDataAdapter("Select * from FeedLibrary where category='Grass / Legume'", Connection);
        DataTable Dtable = new DataTable();
        DataA.Fill(Dtable);
        frm2.FeedSelectListBox .DataSource = Dtable;

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