在mysql数据库的列中搜索空单元格并显示在datagridview上

Question

My application requires to search the incompleted projects in our task management software. And for that i am trying to implement a way i could read our MySQL database for incomplete projects and display them on the screen. The project will be incomplete if the particular cell is a "null value". The project is completed when the cell says "Completed". I am trying to search for all null values in a row and display them on to the DataGridView with visual basic C#. The code i tried is the following, unfortunately it didn't work:

private void button4_Click(object sender, EventArgs e)
{
    DataView DV = new DataView(dt);
    DV.RowFilter = string.Format("BackSheetAssembled LIKE '%{0}%'", DBNull.Value );
    dataGridView1.DataSource = DV;
}

I tried the same method with substituting DBNull.Value with a text box and it works fine and search the database for those texts, but it doesn't work for a Null value.

Answer 1

尝试这个

DV.RowFilter = "Isnull(BackSheetAssembled,'') = ''";

Answer 2

DV.RowFilter = "BackSheetAssembled is null";

Example:

var table = new DataTable();
table.Columns.Add(new DataColumn("Id"));
table.Columns.Add(new DataColumn("Name"));
table.Rows.Add(new object[] { 123, "Name1" });
table.Rows.Add(new object[] { 234, "Name2"});
table.Rows.Add(new object[] { null, "Name3" });

var view = new DataView(table);
view.RowFilter = "Id is null";

for (int i = 0; i < view.Count; i++)
   Console.WriteLine(view[i][1].ToString());

Console.ReadLine();

Outputs: Name3