Input string was not in a correct format.

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Hi,

I have error in my coding. I am trying to increase count on a click. But i am getting an error " Input string was not in a correct format". Please Help me with this

C#

public void GridView1_SelectedIndexChanged(object sender, EventArgs e)
    {
        int count = 1;
        SqlConnection con = new SqlConnection("server=ADMIN-PC\\SQLEXPRESS;initial catalog=content;integrated security=true");
        con.Open();
        SqlCommand cmd;
            cmd = new SqlCommand("select * from usrimg where ImageName='" + GridView1.SelectedDataKey["ImageName"].ToString() + "'", con);
        SqlDataReader dr = cmd.ExecuteReader();
        if (dr.Read())
        {
            count = Convert.ToInt32(dr[2]);//Input string was not in a correct format.
            count++;
            dr.Close();
            cmd = new SqlCommand("update usrimg set count =" + count + "where ImageName='" + GridView1.SelectedDataKey["Image Name"].ToString() + ")", con);
            cmd.ExecuteNonQuery();
            con.Close(); 
        }

Posted 4-Apr-15 4:31am

Prabhu92

Updated 4-Apr-15 4:42am

RajeeshMenoth

v2

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Comments

[no name] 4-Apr-15 10:49am

Then check your database value "dr[2]"?

Prabhu92 6-Apr-15 0:45am

How to check the database value... I am quite new to this

Prabhu92 6-Apr-15 0:46am

dr[2] is actually a column number right?

Prabhu92 6-Apr-15 2:10am

Object cannot be cast from DBNull to other types i am getting this error

3 solutions

Solution 3

Hi this is mayur

C#

using(var cmd = new SqlCommand("UPDATE usrimg SET [count] = [count] + 1 where ImageName =@ImageName", con))

Posted 5-Apr-15 19:44pm

Member 11572050

Updated 5-Apr-15 19:48pm

v2

Comments

Prabhu92 6-Apr-15 2:13am

My column "count" is not updating.

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OriginalGriff · Accepted Answer · 2015-04-04T04:50:00

This is a good example of why you shouldn't use SELECT * FROM in SQL queries - you don't know what will be returned (and it can often return stuff you don't need, making it inefficient). Any fields you didn't think about, any database changes, and your code starts to do unusual things...

Instead, only request the fields you are going to use:

C#

cmd = new SqlCommand("SELECT MyColumnWithANumberInIt FROM usrimg WHERE ImageName=@IN", con);
cmd.Parameters.AddWithValue("@IN", GridView1.SelectedDataKey["ImageName"]);
SqlDataReader dr = cmd.ExecuteReader();
if (dr.Read())
{
    count = Convert.ToInt32(dr["MyColumnWithANumberInIt"]);

And please, don't do DB access the way you have been. Do not concatenate strings to build a SQL command. It leaves you wide open to accidental or deliberate SQL Injection attack which can destroy your entire database. Use Parametrized queries instead, as I did above.

DamithSL · Accepted Answer · 2015-04-04T07:38:00

Solution 2

you can use single sql statement to do the update and you better use parameterized sql statement

C#

using(var con = new SqlConnection("server=ADMIN-PC\SQLEXPRESS;initial catalog=content;integrated security=true"))
using(var cmd = new SqlCommand("UPDATE usrimg SET [count] = [count] + 1 where ImageName =@ImageName", con))
{
  con.Open();
  cmd.Parameters.AddWithValue("@ImageName", GridView1.SelectedDataKey["ImageName"].ToString());
  cmd.ExecuteNonQuery();
}

Posted 4-Apr-15 7:38am

DamithSL

Updated 5-Apr-15 19:26pm

v2

Comments

Prabhu92 6-Apr-15 0:57am

I am getting an error invalid column count

DamithSL 6-Apr-15 1:28am

I have updated the sql statement, count is reserved keyword and you need to use [] when you use it as column name.

Prabhu92 6-Apr-15 1:36am

I will give a try

Prabhu92 6-Apr-15 2:06am

My column "count" is not updating. I mean Count = count + 1 is not increasing

Input string was not in a correct format.

3 solutions

Solution 1

Solution 2

Solution 3

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