How to set “Unavailable” word for null values in DataGridView

问题

I have an employees table in which first number is set as not null and second number that can be **null* so when I call the employees information to view their information in DataGridView the null values appear as empty cells but I want to show "Unavailable" word instead of the empty cell , so how can I do this?

回答1:

You can use either of these options:

Set NullValue property of DefaultCellStyle of the column. It sets the cell display value corresponding to a cell value of DBNull.Value or null.
Use CellFormatting event and set e.Value when the value of cell is DBNull.Value or null

Example 1

this.dataGridView1.Columns[1].DefaultCellStyle.NullValue = "Unavailable";

Example 2

void dataGridView1_CellFormatting(object sender, DataGridViewCellFormattingEventArgs e)
{
    if (e.ColumnIndex < 0 || e.RowIndex < 0)
        return;

    if (e.Value == DBNull.Value || e.Vallue == null)
        e.Value = "Unavailable";
}

回答2:

Change your Select statement to something like this (use CASE WHEN):

SELECT Id, CASE WHEN SecondNumber IS NULL THEN 'Unavailable' ELSE SecondNumber END AS SecondNumber
FROM yourTable

回答3:

This solution would also include an extension method so please make the following extension method.

this is what we will need to set the values of the grid in a more clean way (optional though)

 public static void ApplyAction<T>(this IEnumerable<T> source, Action<T> action)
 {
     foreach (var entity in source)
     {
         action(entity);

     }
 }

now all you have to do is going to be the following :

dataGridView1.Rows.OfType<DataGridViewRow>().Where(c => c.Cells[ColumnName.Index].Value == null).ApplyAction(new Action<DataGridViewRow>(c => c.Cells[ColumnName.Index].Value = "Unavailable"));

来源：https://stackoverflow.com/questions/39931566/how-to-set-unavailable-word-for-null-values-in-datagridview

标签

sql-server

winforms

datagridview