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You need to check it to see if it's a DBNull before you attempt to convert it. Suppose that you are using a DataReader, you could do this
if (!myDataReader.IsDBNull(0))
myText = myDataReader.GetString(0);
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Pete O'Hanlon,
Thanx for your response, bud what if i don't use a datareader? and have only a select. this how my code looks like:
SqlCommand comm00 = new SqlCommand("select Cmp_nr from Companies where Cmp_name='" + companyName + "'", myconn);
companyName = (string)comm00.ExecuteScalar();
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Use the IsNull SQL Command and convert it on the server.
Also, you should use parameters in your queries, not appending strings. Using parameters prevents your select statement being open to an SQL Injection attacks. (Said with a broad Scottish accent...)
"More functions should disregard input values and just return 12. It would make life easier." - comment posted on WTF
"This time yesterday, I still had 24 hours to meet the deadline I've just missed today."
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For simple select statements such as this, I would use ISNULL in the sql command...
For example, using the code you included:
SqlCommand comm00 = new SqlCommand();
string commSQL = "SELECT ISNULL(Cmp_nr, '') AS Cmp_nr FROM Companies where Cmp_name=@cmpName";
SqlPararameter cmpParam = new SqlParameter("@cmpName", SqlDbType.VarChar, 50);
//note: 50 should be changed to the field length of your db field Cmp_name
cmpParam.Value = companyName;
comm00.Parameters.Add(cmpParam);
comm00.Connection = myconn;
comm00.CommandText = commSQL;
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string companyName = "";
object result = comm00.ExecuteScalar();
if(result != DBNull.Value)
companyName = (string) result;That will work.
Also, use parameterized queries. Your code has a security hole and is prone to SQL injection attacks. See this article[^].
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Djavid j wrote: SqlCommand comm00 = new SqlCommand("select Cmp_nr from Companies where Cmp_name='" + companyName + "'", myconn);
This query, in short, is devil's palace. I mean it is subject to SQL Injection attacks. Did you consider having it as a Stored Procedure instead?
Vasudevan Deepak Kumar
Personal Homepage
Tech Gossips
Yesterday is a canceled check. Tomorrow is a promissory note. Today is the ready cash. USE IT.
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Depends where the code is. Obviously, whatever construct you're using ( data reader, data table, etc ), you're not checking if it has data in it before you try to read it.
Christian Graus - Microsoft MVP - C++
"also I don't think "TranslateOneToTwoBillion OneHundredAndFortySevenMillion FourHundredAndEightyThreeThousand SixHundredAndFortySeven()" is a very good choice for a function name" - SpacixOne ( offering help to someone who really needed it ) ( spaces added for the benefit of people running at < 1280x1024 )
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I have a class that inherits from the datagridview component and within this class i am setting the datasource. My problem isthat the datasource is very large and i get a System.OutOfMemory Exception. I want to prevent the rows from populating at designtime. My code is below:
<br />
public class MembersView:DataGridView<br />
{<br />
public MembersView()<br />
{<br />
this.DataSource = Customer.Instance.GetAllCustomers();<br />
}<br />
}<br />
I still want the designer to show my the columns. Ay suggestions?
-- modified at 16:02 Sunday 18th November, 2007
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Check the DesignMode property
if(DesignMode)
DataSource = Dummy
else
DataSource = Customer.Instance.GetAllCustomers();
only two letters away from being an asset
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I came across this little unknown facet of .net a few days ago and today I decided to build a sample application to test this out. I followed the instructions as to how to apply SNIP specified on this site: http://www.morganskinner.com/Articles/StrongNameIdentityPermission/[^]
When I called my assembly in an unsigned project, it failed to give me any warning and my method from my signed class library executed.
Is this is happening because the signed class library is running in full trusted zone ?
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I create bitmap;
Bitmap myBitmap = new Bitmap(150, 50);
Graphics g = Graphics.FromImage(myBitmap);
And draw picture;
g.FillRectangle()
g.DrawString()
I use myBitmap.Save() method and show image using IMAGE component img.ImageUrl = "..."; property.
But I don't want to save image. How can I show bitmap without using save() function ?
Best Regards...
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Have you tried Graphics.DrawImage ?
only two letters away from being an asset
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Assign the bitmap to the Image property of the control.
Experience is the sum of all the mistakes you have done.
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I use Visual.net 2005. And I use image control (component) on asp.net web site.
How can I assign the bitmap to the Image property of the control ?
Best Regards...
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Oh, it's an ASP.NET question.
Then you can't do it that way. The browser will fetch the image in a separate request, so you will have to create the image in a separate page.
Make a page that creates the image and sends it to the response stream, then use the name of that page as url in the image control.
Experience is the sum of all the mistakes you have done.
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The ASP.NET forum is the place for ASP.NET questions. Why would anyone assume from your original post that this was an ASP.NET question ?
Christian Graus - Microsoft MVP - C++
"also I don't think "TranslateOneToTwoBillion OneHundredAndFortySevenMillion FourHundredAndEightyThreeThousand SixHundredAndFortySeven()" is a very good choice for a function name" - SpacixOne ( offering help to someone who really needed it ) ( spaces added for the benefit of people running at < 1280x1024 )
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Sorry, but this question is releated about image processing. Accually, all question releated about .NET classes, so all question move to .NET framework message board. Isn't it ???
Best Regard...
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No, this question has absolutely nothing to do with image processing.
1 - drawing on an image is not image processing, and
2 - your question is how to pass an image you have created in memory into a web page, right ? That's an ASP.NET question. Rendering it in a winforms app is both trivial, and completely different. That's why all the initial answers you got were useless to you. And that's my point. I don't care where you ask, there is some crossover, a lot of questions in the ASP.NET forum *are* C# questions. But, asking this question in this forum has meant it's taken you longer to get towards an answer, as people assumed you were asking something different.
Christian Graus - Microsoft MVP - C++
"also I don't think "TranslateOneToTwoBillion OneHundredAndFortySevenMillion FourHundredAndEightyThreeThousand SixHundredAndFortySeven()" is a very good choice for a function name" - SpacixOne ( offering help to someone who really needed it ) ( spaces added for the benefit of people running at < 1280x1024 )
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Actually If I use oBitmap.Save(Response.OutputStream, ImageFormat.Jpeg); so image created without physically. But how to initialize Image1.ImageUrl = "??????".
Best Regards...
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There are two ways to do this:
1 - with a HTTPHandler that passes back the image
2 - by saving the image to your file system first.
Christian Graus - Microsoft MVP - C++
"also I don't think "TranslateOneToTwoBillion OneHundredAndFortySevenMillion FourHundredAndEightyThreeThousand SixHundredAndFortySeven()" is a very good choice for a function name" - SpacixOne ( offering help to someone who really needed it ) ( spaces added for the benefit of people running at < 1280x1024 )
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Christian Graus wrote: There are two ways to do this:
1 - with a HTTPHandler that passes back the image
2 - by saving the image to your file system first.
Or perhaps the most obvious:
3 - with a page that passes back the image
Experience is the sum of all the mistakes you have done.
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using System;
public class AvgPrime
{
public static void Main()
{
double c=0,y=0,p=0;
int i,j;
bool isPrime;
for(i=2; i <= 100; i++)
{
isPrime = true;
for(j=2; j <= i/2; j++)
{
if(i % j == 0)
{
isPrime = false;
}
}
if(isPrime)
{
y = y + 1;
c = c + i;
}
}
p = c/y;
Console.WriteLine("The avg of all prime numbers from 1 to 100 is {0}",p);
}
}
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Oh come on, if this isn't homework, what else is?
Some people never learn... 
Regards,
mav
--
Black holes are the places where God divided by 0...
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How about adding some explanatory text lines that start with a double slash?
Things I would like to know:
- why are c and y of type double?
- why is i incremented by one?
- why is j limited to i/2?
- why does the for(j) loop continue when a divisor has been found?
- why are most identifiers single-character?
Luc Pattyn [Forum Guidelines] [My Articles]
this months tips:
- before you ask a question here, search CodeProject, then Google
- the quality and detail of your question reflects on the effectiveness of the help you are likely to get
- use PRE tags to preserve formatting when showing multi-line code snippets
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