C＃winform如果特定的列不为空，如何过滤组合框

Question

例如，我有一个项目表：

ProjectID | ProjectName | EstimateStartDate | EstimateEndDate | ActaulStartDate | ActualEndDate |  
    1     |Liberty Green|    06-26-2017     |   06-30-2017    |    06-26-2017   |   08-30-2017  |
    2     |   Wharton   |    06-26-2017     |   06-30-2017    |       null      |   null        |

因此，基本上，我希望所有其中ActualStartDate和ActualEndDate为null的行都显示在ComboBoxProjectName中，而所有非null的行将不再显示在ComboBoxProjectName中。

Answer 1

您可以尝试选择ActualStartDate为null ...的所有行，然后通过datatable设置datasource组合框：

SqlConnection con = new SqlConnection("ConnectionString");
        try
        {
            if (con.State == ConnectionState.Closed) con.Open();
            SqlCommand cmd = new SqlCommand();
            cmd.CommandText = "Select * from Project Table where ActaulStartDate is null and ActualEndDate is null";
            cmd.Connection = con;
            SqlDataAdapter da = new SqlDataAdapter(cmd);
            DataTable dt = new DataTable();
            da.Fill(dt);

            comboBox1.DataSource = dt;
            comboBox1.DisplayMember = "ProjectName";
            comboBox1.ValueMember = "ProjectID";
        }
        catch (Exception)
        {
            throw;
        }
        finally
        {
            if (con.State == ConnectionState.Open) con.Close();
        }