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如何使用多个ComboBox过滤DataGridView？

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我对编码非常陌生，并试图通过小项目学习C＃ .
我花了一个星期或更长时间试图找到解决方案但是虽然有许多线程，但它们对我来说都没有意义，也无法让它发挥作用 .

我有一个带有DataGridView的Form，我想创建6个ComboBox来过滤它 . 全部具有相同的数据源 .
我到目前为止管理DataGridView使用一个ComboBox但不知道如何添加更多 .

我的代码：

using System.Data;
using System.Data.SqlClient;

public partial class frmEmpList : Form
{
    private void frmEmpList_Load(object sender, EventArgs e)
    {
        this.PopulateCombobox();
        this.PopulateDataGridView();
    }

    private void PopulateCombobox()
    {
        string qry = "SELECT DISTINCT LastName FROM Employees";
        string constr = @"Data Source=DESKTOP-Q2B3UUH\SQLEXPRESS;Initial Catalog=PeopleManager;Integrated Security=True";

        using (SqlConnection con = new SqlConnection(constr))
        using (SqlDataAdapter sda = new SqlDataAdapter(qry, con))
        {
            DataTable dt = new DataTable();
            sda.Fill(dt);

            DataRow row = dt.NewRow();
            row[0] = "";
            dt.Rows.InsertAt(row, 0);

            cbLastName.DataSource = dt;
            cbLastName.DisplayMember = "LastName";
            cbLastName.ValueMember = "LastName";
        }
    }

    private void PopulateDataGridView()
    {
        string query = "SELECT EmpID, FirstName, LastName, Role, Grade, Dept, Shift FROM Employees";
        query += " WHERE LastName = @LastName";
        query += " OR ISNULL(@LastName, '') = ''";
        string constr = @"Data Source=DESKTOP-Q2B3UUH\SQLEXPRESS;Initial Catalog=PeopleManager;Integrated Security=True";

        using (SqlConnection con = new SqlConnection(constr))
        using (SqlCommand cmd = new SqlCommand(query, con))
        {
            cmd.Parameters.AddWithValue("@LastName", cbLastName.SelectedValue);
            using (SqlDataAdapter sda = new SqlDataAdapter(cmd))
            {
                DataTable dt = new DataTable();
                sda.Fill(dt);
                dgEmpList.DataSource = dt;
            }
        }
    }

    private void cbLastName_SelectionChangeCommitted(object sender, EventArgs e)
    {
        this.PopulateDataGridView();
    }
}
c# filter datagridview combobox

2 回答

  • 0

    感谢Wanton快速回复！讨厌说，但我没有正确地应用它 . 请看附图：enter image description here

    回复于
  • 0

    我会将 ("@LastName", cbLastName.SelectedValue) 更改为 ("@LastName", string.IsNullOrWhiteSpace(cbLastName.SelectedValue as string) ? DBNull.Value : ((string)cbLastName.SelectedValue).Trim())

    然后

    query += " WHERE LastName = @LastName";
query += " OR ISNULL(@LastName, '') = ''";

    至

    query += " WHERE (@LastName IS NULL OR LastName = @LastName)";

    如果您的查询需要更多过滤器，请添加更多此类过滤器

    query += " AND (@FooBar IS NULL OR FooBar = @FooBar)";

    您还可以通过仅包含脚本中所需的过滤器来创建动态脚本 . 第一个过滤器需要使用 WHERE 和其他 AND

    回复于

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