C# 从datagridview中选定行中的值的ID获取名称

我在gridview中隐藏了Author\u ID和Publisher\u ID。我希望当我单击一行时，Author和Publisher组合框文本填充选定的行值。行中有publisher和author id作为外键，但我想在组合框文本中显示它们的名称。如何访问它们

    private  void gridViewBook_CellContentClick(object sender, DataGridViewCellEventArgs e)
    {

        gridViewBook.CurrentRow.Selected = true;

        txtID.Text = gridViewBook.Rows[e.RowIndex].Cells["BOOK_ID"].FormattedValue.ToString();
        txtISBN.Text = gridViewBook.Rows[e.RowIndex].Cells["ISBN"].FormattedValue.ToString();
        txtName.Text = gridViewBook.Rows[e.RowIndex].Cells["BOOK_NAME"].FormattedValue.ToString();
        txtPage.Text = gridViewBook.Rows[e.RowIndex].Cells["PAGE"].FormattedValue.ToString();
        txtLang.Text = gridViewBook.Rows[e.RowIndex].Cells["LANGUAGE"].FormattedValue.ToString();
        comboBoxAuthor.Text= gridViewBook.Rows[e.RowIndex].Cells["AUTHOR_ID"].FormattedValue.ToString();
        
        comboBoxPublisher.Text = gridViewBook.Rows[e.RowIndex].Cells["PUBLISHER_ID"].FormattedValue.ToString();
    }

我只能访问他们的ID。 我像这样填充组合框

    private void fillAuthorBox()
    {
        conn.Open();

        SqlCommand cmd = new SqlCommand("SELECT * FROM AUTHOR ", conn);
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataTable dt = new DataTable();
        da.Fill(dt);

        comboBoxAuthor.ValueMember = "AUTHOR_ID";
        comboBoxAuthor.DisplayMember = ("AUTHOR_FULLNAME");
        comboBoxAuthor.DataSource = dt;

        conn.Close();
    }

    private void fillPublisherBox()
    {
        conn.Open();

        string query = " SELECT * FROM PUBLISHER ";
        SqlCommand cmd = new SqlCommand(query, conn);
        SqlDataAdapter da = new SqlDataAdapter(cmd);
        DataTable dt = new DataTable();
        da.Fill(dt);

        comboBoxPublisher.ValueMember = "PUBLISHER_ID";
        comboBoxPublisher.DisplayMember = "PUBLISHER_NAME";
        comboBoxPublisher.DataSource = dt;

        conn.Close();

    }

---

我首先看的是

fillAuthorBox（）

和

fillPublisherBox（）

。在某些地方，您有调用这些方法的代码。我们在问题中看不到这一点，因此我将假设它是一个通用的表单加载方法，如下所示：

void form_Load(...)
{
    fillAuthorBox();
    fillPublisherBox();
}

void form_Load(...)
{
    comboBoxAuthor.ValueMember = "AUTHOR_ID";
    comboBoxAuthor.DisplayMember = "AUTHOR_FULLNAME";
    comboBoxAuthor.DataSource = getAuthorNames();

    comboBoxPublisher.ValueMember = "PUBLISHER_ID";
    comboBoxPublisher.DisplayMember = "PUBLISHER_NAME";
    comboBoxPublisher.DataSource = getPublisherNames();
}

我们可以做得更好。这些方法中存在一些常见错误，我将在下面纠正这些错误：

//only re-use the connection string, NOT the whole connection object
private connString As String = "connection string here";

//return a value, don't touch any form controls
// even better if these methods are moved to a different class
public DataTable getAuthorNames()
{        
    using (var conn = new SqlConnection(connString))
    // Don't SELECT * if you don't need all the fields!
    using (var cmd = new SqlCommand("SELECT AUTHOR_ID, AUTHOR_FULLNAME FROM AUTHOR ", conn))
    using (var da = new SqlDataAdpater(cmd))
    { 
        var dt = new DataTable();
        da.Fill(dt); // Fill() automatically opens and closes the connection object
        return dt;
    } 
    //using blocks make sure your items are fully disposed when the block closes, 
    // **even if an exception is thrown!**
}

public DataTable getPublisherNames()
{
    ​using (var conn = new SqlConnection(connString))
    using (var cmd = new SqlCommand("SELECT PUBLISHER_ID, PUBLISHER_NAME FROM PUBLISHER", conn))
    using (var da = new SqlDataAdpater(cmd))
   ​ { 
        ​var dt = new DataTable();
       ​ da.Fill(dt);
       ​ return dt;
   ​ }     
}

现在，我的原始表单_Load（）如下所示：

void form_Load(...)
{
    fillAuthorBox();
    fillPublisherBox();
}

void form_Load(...)
{
    comboBoxAuthor.ValueMember = "AUTHOR_ID";
    comboBoxAuthor.DisplayMember = "AUTHOR_FULLNAME";
    comboBoxAuthor.DataSource = getAuthorNames();

    comboBoxPublisher.ValueMember = "PUBLISHER_ID";
    comboBoxPublisher.DisplayMember = "PUBLISHER_NAME";
    comboBoxPublisher.DataSource = getPublisherNames();
}

---

从这里开始，我们可以继续在有人单击网格中的某一行时选择正确的条目。为此，我们不想设置

Text

属性，而是想更改所选的项目。因为我们知道

ValueItem

，所以可以通过

SelectedValue

属性来实现

private  void gridViewBook_CellContentClick(object sender, DataGridViewCellEventArgs e)
{
    gridViewBook.CurrentRow.Selected = true;

    txtID.Text = gridViewBook.Rows[e.RowIndex].Cells["BOOK_ID"].FormattedValue.ToString();
    txtISBN.Text = gridViewBook.Rows[e.RowIndex].Cells["ISBN"].FormattedValue.ToString();
    txtName.Text = gridViewBook.Rows[e.RowIndex].Cells["BOOK_NAME"].FormattedValue.ToString();
    txtPage.Text = gridViewBook.Rows[e.RowIndex].Cells["PAGE"].FormattedValue.ToString();
    txtLang.Text = gridViewBook.Rows[e.RowIndex].Cells["LANGUAGE"].FormattedValue.ToString();

    comboBoxAuthor.SelectedValue = gridViewBook.Rows[e.RowIndex].Cells["AUTHOR_ID"].Value;        
    comboBoxPublisher.SelectedValue = gridViewBook.Rows[e.RowIndex].Cells["PUBLISHER_ID"].Value;
}

---

但是在这里要小心！我对WinForms有点不习惯，我不记得这对于不匹配的类型有多宽容。组合框

ValueMember

可能是一个

int

或

DataGridViewCell

，但是我们使用

字符串来设置
SelectedValue
，这可能不起作用。您可能需要将字符串转换回int，或者查找值的索引来更新SelectedIndex属性。
不要在任何地方重复使用相同的SqlConnection（
conn
）。它干扰了一种称为连接池的功能，因此（在
使用
块中）大多数查询都会遇到这种情况。另外，
.Fill（）
方法已经为您打开和关闭了连接。最后，构建数据访问方法以返回数据比直接更新控件要好得多。让调用这些方法的代码更新表单中的控件。是否考虑过在每个文本框中添加一个
数据绑定
？类似于…
txtISBN.DataBindings.Add（“Text”，gridViewBook.DataSource，“ISBN”）…这将消除网格
CellContentClick
事件中的所有代码，并完成相同的任务。非常感谢。通常我不会为Windows窗体编写代码，但这是我必须完成的项目的一部分。因为我对这门学科知之甚少，所以我需要帮助，尽管这很容易。谢谢你的帮助，它运行得很顺利@乔尔科霍恩