C# 如何使用c对combobox进行Linq查询#

我有一个让我发疯的简单问题。我试图查询一个数据实体，在我尝试引用外部数据之前，一切都正常。在下面的代码中（这非常有效），我想将.where clientID==15更改为。如果客户端ID是组合框中显示的值，则组合框valuemember是一个整数：

 private void cboxcos_SelectionChangeCommitted(object sender, EventArgs e)
    {
        using (var context2 = new tvdm())
        {
            var cus = context2.tblContacts
                .Where(c => c.ClientID == 15)
               .Select(c => new {c.LastName, c.FirstName, c.JobTitle, c.Telephone, c.Mobile, c.EMail })
                .OrderBy(p => p.LastName)
                .ToList();

            dataGridView1.DataSource = cus;               

        }
    }

任何简单的帮助都将不胜感激

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我将VS2015社区与C#和EF6一起使用，我想您需要

var cus = context2.tblContacts
    .Where(c => c.ClientID == Convert.ToInt32(myComboBox.SelectedItem))
    .Select(c => new {c.LastName, c.FirstName, c.JobTitle, c.Telephone, c.Mobile, c.EMail })
    .OrderBy(p => p.LastName)
    .ToList();

---

我想你需要像这样的东西

var cus = context2.tblContacts
    .Where(c => c.ClientID == Convert.ToInt32(myComboBox.SelectedItem))
    .Select(c => new {c.LastName, c.FirstName, c.JobTitle, c.Telephone, c.Mobile, c.EMail })
    .OrderBy(p => p.LastName)
    .ToList();

---

首先获取值，将其转换为正确的类型，然后在linq查询中使用该参数：

    private void cboxcos_SelectionChangeCommitted(object sender, EventArgs e)
    {
        int value = (int)comboBox1.SelectedValue;
        using (var context2 = new tvdm())
        {
            var cus = context2.tblContacts
                .Where(c => c.ClientID == value)
               .Select(c => new { c.LastName, c.FirstName, c.JobTitle, c.Telephone, c.Mobile, c.EMail })
                .OrderBy(p => p.LastName)
                .ToList();

            dataGridView1.DataSource = cus;

        }
    }

---

首先获取值，将其转换为正确的类型，然后在linq查询中使用该参数：

    private void cboxcos_SelectionChangeCommitted(object sender, EventArgs e)
    {
        int value = (int)comboBox1.SelectedValue;
        using (var context2 = new tvdm())
        {
            var cus = context2.tblContacts
                .Where(c => c.ClientID == value)
               .Select(c => new { c.LastName, c.FirstName, c.JobTitle, c.Telephone, c.Mobile, c.EMail })
                .OrderBy(p => p.LastName)
                .ToList();

            dataGridView1.DataSource = cus;

        }
    }

}

---

}

事实上，我的结局是：

private void cboxcos_SelectionChangeCommitted(object sender, EventArgs e)
    {
        using (var context2 = new tvdm())
        {
            int value = (int)cboxcos.SelectedValue;
            var cus = context2.tblContacts
                .Where(c => c.ClientID == value)
               .Select(c => new {c.LastName, c.FirstName, c.JobTitle, c.Telephone, c.Mobile, c.EMail })
                .OrderBy(p => p.LastName)
                .ToList();

            dataGridView1.DataSource = cus;               

        }
    }

---

事实上，我最终得到了：

private void cboxcos_SelectionChangeCommitted(object sender, EventArgs e)
    {
        using (var context2 = new tvdm())
        {
            int value = (int)cboxcos.SelectedValue;
            var cus = context2.tblContacts
                .Where(c => c.ClientID == value)
               .Select(c => new {c.LastName, c.FirstName, c.JobTitle, c.Telephone, c.Mobile, c.EMail })
                .OrderBy(p => p.LastName)
                .ToList();

            dataGridView1.DataSource = cus;               

        }
    }

---

你得到了什么错误？我只是不能让它达到可以编译的状态，intellisense只是在它下面加下划线。所以你得到了一个编译器错误。哪一个？你得到了什么错误？我只是不能让它达到可以编译的状态，intellisense只是在它下面加下划线。所以你得到了一个编译器错误。哪一个？很好用，非常感谢你的帮助。我现在可以开始理解它，然后推进我的项目。这非常有效，非常感谢你的帮助。我现在可以开始理解它，然后推进我的项目。