Object cannot be cast from DBNull to other types

Praveen Maurya

i want to calculate sum table values but at startup my application the table is having null value and it show error like .....Object cannot be cast from DBNull to other types

Please suggest how i can solve this.

SqlDataAdapter sda21 = new SqlDataAdapter("select * from sale_total", con);
DataTable dt21 = new DataTable();
sda21.Fill(dt21);
int sum = Convert.ToInt32(dt21.Compute("SUM(gtot)", string.Empty));
SqlDataAdapter sda22 = new SqlDataAdapter("select * from exp_total", con);
DataTable dt22 = new DataTable();
sda22.Fill(dt22);
int sum1 = Convert.ToInt32(dt22.Compute("SUM(gtot)", string.Empty));
metroTile13.Text = "\u20B9 " + sum1.ToString() + ".00";
if (sum1 < sum)
{
int sum2 = sum - sum1;
label2.Text = "\u20B9 " + sum2.ToString() + ".00";
metroTile6.Text = "\u20B9 " + sum2.ToString() + ".00";
}
if (sum1 > sum)
{
int sum2 = sum1 - sum;
label2.Text = "\u20B9 " + sum2.ToString() + ".00";
metroTile6.Text = "\u20B9 " + sum2.ToString() + ".00";
}

6 Replies

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Chirag Khabaria8y ago
Not looking for the functionality, what I meant how did you implement the sample code which I gave you .. what error you got after using the sample code.. and what kind of dataset you are using .. that is causing the dbnull issue.. ?
Praveen Maurya8y ago
Chirag .... I am working on a billing project and incventry management..
i used this code for calculate cash in hand in the system which means total sales and expense will be add or deduct.. but at the first the databse have to be null and when user sell any thing or expens any thing it will calculate and show..

Actually i am using tab control so the page code is very big hope u can understand
Chirag Khabaria8y ago
Can you provide the details, what you tried.. and how did you implement it..?

Post the code snippet and also some sample data.
Praveen Maurya8y ago
Sorry Chirag this code not helped me any other suggestion.
Goran Bibic8y ago
First step, on all cells write 0 (dont have null value) and try...
Chirag Khabaria8y ago
1. // See if this works for you..
2. public static int GetInt(object obj)
3. {
4. int _value = 0;
5. return obj == DBNull.Value ? 0 : (int.TryParse((string)obj, out _value) ? _value : 0);
6. }
8. // call sum function like this..
10. int sum = GetInt(dt21.Compute("SUM(gtot)", string.Empty))