How to check null column values in SQL Database, C#

Question

I'm using dataGridView in Windows Forms to show the database and want to color it. If [Solver] column is NULL it should paint LightSalmon, else LightGreen. However even if the column value is NULL it still see it as not null and paint into LightGreen.

This is my table:
      [Id]
      [Employee]
      [Section]
      [Machine]
      [Station]
      [MachNo]
      [Area]
      [Type]
      [Desc]
      [Recommendation]
      [Date]
      [Solver]
      [Process]


public void Color()
{
    for(int i = 0; i< dataGridView1.Rows.Count; i++)
        if (DBNull.Value.Equals(dataGridView1.Rows[11]))
        {
            dataGridView1.Rows[i].DefaultCellStyle.BackColor = Color.LightSalmon;
        }
        else
        {
            dataGridView1.Rows[i].DefaultCellStyle.BackColor = Color.LightGreen;
        }   
}

GRidView.Column datatype is not same to DBNull

Ed Bangga
– Ed Bangga

2019-09-27 08:55:14 +00:00
Commented Sep 27, 2019 at 8:55 — Ed Bangga
– Ed Bangga, Commented Sep 27, 2019 at 8:55
Also try implementing dataGridView1.Refresh().

CodeRed
– CodeRed

2019-09-27 08:57:57 +00:00
Commented Sep 27, 2019 at 8:57 — CodeRed
– CodeRed, Commented Sep 27, 2019 at 8:57

Prasad Telkikar · Accepted Answer · 2019-09-27 10:03:53Z

1

[Solver] (11th column) is a column not a row, so you need to check that column of each row is null or not

public void Color()
{
    for(int i = 0; i< dataGridView1.Rows.Count; i++)
    {
        if (dataGridView1.Rows[i].Cells[11].Value == null || dataGridView1.Rows[i].Cells[11].Value == DBNull.Value)
        {
             dataGridView1.Rows[i].DefaultCellStyle.BackColor = Color.LightSalmon;
        }    
        else
        {
            dataGridView1.Rows[i].DefaultCellStyle.BackColor = Color.LightGreen;
        }
    }
}

edited Sep 27, 2019 at 10:03

answered Sep 27, 2019 at 9:01

Prasad Telkikar

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Comments

Rahul · Accepted Answer · 2019-09-27 08:57:58Z

1

Rather use the Cells property on that row like

if (DBNull.Value.Equals(dataGridView1.Rows.Cells[11].Value))

answered Sep 27, 2019 at 8:57

Rahul

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Comments

sri harsha · Accepted Answer · 2019-09-27 09:00:11Z

0

You can use like below

dataGridView1.Rows[i].DefaultCellStyle.BackColor = dataGridView1.Rows[i].Cells[11].Value == null ? 
                                                          Color.LightSalmon : Color.LightGreen

or

dataGridView1.Rows[i].DefaultCellStyle.BackColor = dataGridView1.Rows[i].Cells[11].Value == DBNull.Value ? 
                                                  Color.LightSalmon : Color.LightGreen

answered Sep 27, 2019 at 9:00

sri harsha

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Comments

Solanki Sagar · Accepted Answer · 2019-09-27 11:07:57Z

0

for(int i = 0; i< dataGridView1.Rows.Count; i++)
    {  
        if (dataGridView1.Rows[i].Cells[11].Value == null || 
        dataGridView1.Rows[i].Cells[11].Value == DBNull.Value)
    {
         dataGridView1.Rows[i].DefaultCellStyle.BackColor = Color.Red;
    }    
    else
    {
        dataGridView1.Rows[i].DefaultCellStyle.BackColor = Color.Green;
    }
}

answered Sep 27, 2019 at 11:07

Solanki Sagar

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