There is no row at position 0

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Hello I just need another help based on my last question

but the problem is little different

C#

SqlCommand commanduser = new SqlCommand("SELECT * from Users  WHERE Username = @Username", cs);
            commanduser.Parameters.Add("@Username", SqlDbType.NVarChar);
            commanduser.Parameters["@Username"].Value = username.Text;
 
            SqlDataAdapter dataAdapteruser = new SqlDataAdapter(commanduser);
 
            DataTable dataTableuser = new DataTable();
 
            dataAdapteruser.Fill(dataTableuser);
 
            userid.username = (String)dataTableuser.Rows[0]["Username"];

on this bolded line I get There is no row at position 0,

since userid comes from the class which I made like this

C#

public class User
    {
        public  User()
        {
        }
        private string username;
        

        public string Username
        {
            get
            {

                return username;
            }
            set { username = value; }
        }

I am guessing I have to write some code in case I have no value to return, but hehe don't know how

Posted 18-Aug-13 23:33pm

shonezi

Updated 18-Aug-13 23:37pm

Code-Hunt

v3

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Jameel VM 19-Aug-13 5:37am

Please run the query in sql server directly and check whether it's return any records.

2 solutions

Solution 2

no you do not need to write more code.
its clearing saying that your datatable has no row means you have no record into datatable.

check the query in sql first.

Posted 18-Aug-13 23:38pm

S.P.Tiwari

Updated 18-Aug-13 23:40pm

v2

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OriginalGriff · Accepted Answer · 2013-08-18T23:36:00

Solution 1

C#

if (dataTableuser.Rows.Count <= 0)
   {
   // there are no rows to play with...
   }

Posted 18-Aug-13 23:36pm

OriginalGriff

Comments

shonezi 19-Aug-13 5:40am

THANK YOU GRIFF!!! just to ask, is there a possibility to place if question in get set property of the class that I have of the username, just wondering

OriginalGriff 19-Aug-13 6:03am

No - the User class does not know where it is being used: it has no access to the caller variables!

That's a bit like asking "Can my phone please talk to my mother because I don't have an hour to spare" :laugh:

shonezi 19-Aug-13 6:14am

:) guess I asked to much ::) :) :) thanks Griff

OriginalGriff 19-Aug-13 6:25am

You're welcome!

CodeBlack 19-Aug-13 6:04am

instead of you can use
if(dataTableuser.Rows.Any())
{
// Do your work
}

this will reduce the compiler execution time. becase for "Count" compiler will check for all the rows and get the count and for "Any" compiler will check for the first row only and return true or false based on that.

shonezi 19-Aug-13 6:13am

It says Rows don't hold definiton for action Any

CodeBlack 19-Aug-13 6:19am

ohhh i forgot that you are using DataTable.

OriginalGriff 19-Aug-13 6:22am

Are you sure?
Have you tried?
Did you know that Any is a Linq method, and has an appreciable overhead?
Try it:
List<string> s = new List<string>();
for (int i = 0; i < 100000; i++)
{
s.Add("Hello");
}
Stopwatch s1 = new Stopwatch();
int x1 = 0;
s1.Start();
for (int x = 0; x < 1000000; x++)
{
if (s.Count > 0)
{
x1++;
}
}
s1.Stop();
Stopwatch s2 = new Stopwatch();
int x2 = 0;
s2.Start();
for (int x = 0; x < 1000000; x++)
{
if (s.Any())
{
x2++;
}
}
s2.Stop();
Console.WriteLine("{0}:{1}", s1.ElapsedMilliseconds, s2.ElapsedMilliseconds);
You will find that the Any method is about 10 times slower - probably because an IEnumerable maintains an items count with it adds and subtracts when you call it's methods...

CodeBlack 19-Aug-13 6:37am

Nice example OriginalGriff. That makes me more clear and improve my knowledge where i was wrong for ANY and COUNT. Thanks for the explanation. :)

OriginalGriff 19-Aug-13 6:42am

You're welcome!

shonezi 19-Aug-13 6:42am

since I am amateur, I will just say thank you both :) :) :) :)