ExecuteScalar returns null.

Hi, i am facing a problem. i want to retrieve a query result from my database, but my query happeneds to return null, but i wrote a method using ExecuteScalar to retrive the value, but if the qurey return null, it will be caught by the catch (Exception ex){} part. How should i go about it? could someone please advice me?

Code:

// execute a select command and return a single result as a string
public static string ExecuteScalar(DbCommand command)
{
// The value to be returned
string value = "";
// Execute the command making sure the connection gets closed in the end
try
{
// Open the connection of the command
command.Connection.Open();
// Execute the command and get the number of affected rows
value = command.ExecuteScalar().ToString();
}
catch (Exception ex)
{
//Log eventual errors and rethrow them
throw ex;
}
finally
{
// Close the connection
command.Connection.Close();
}
// return the result
return value;
}

However i got another method which does select query that returns a datatable. But i don't know how retrieve a row out from a datatable, For example using a datareader will be like dreader[0].ToString. But in datatable's case how should i do that? Can someone please advice me thanks..

Code:

public static DataTable ExecuteSelectCommand(DbCommand command)
{
// The DataTable to be returned
DataTable table;
// Execute the command making sure the connection gets closed in the end
try
{
// Open the data connection
command.Connection.Open();
// Execute the command and save the results in a DataTable
DbDataReader reader = command.ExecuteReader();
table = new DataTable();
table.Load(reader);
// Close the reader
reader.Close();
}
catch (Exception ex)
{
//Utilities.SendErrorLogEmail(ex);
throw ex;
}
finally
{
// Close the connection
command.Connection.Close();
}
return table;
}

1 Reply

Know the answer? Post it — somebody with the same question will find it here.

sanoj kumar20y ago
Using data reader is the best way but try to write a simple function
justlike Nvl in oracle
public Object Nvl(Object exp,Object sub)

{

try

{

if(exp.Equals(null) || exp.ToString().Length<1)

return sub;

else

return exp;

}

catch(NullReferenceException nx)

{

return sub;

}

}
and pass the values.
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