Question

take a look at the below while loop.

SqlDataReader dr;

while (dr.Read())
{

Response.Write("insert into test values(N'"+dr[0]+"', N'"+dr[1]+"'),<br>");

}

I am just printing something with a comma at the end (before that
). But For the last time when it gets printed, i dont want that comma.
How to find out that this loop is executing for the last time? so that i can avoid this comma getting printed by modifying it.

Answer 1

In general, it’s not really possible no know if you are on a last iteration of a while loop.
You could use a loop-and-a-half, where not the last, but the first run of the loop is different, like this:

SqlDataReader dr = ...;

if (dr.Read())
{
  //no comma
  Response.Write("insert into test values(N'"+dr[0]+"', N'"+dr[1]+"')");
}

while (dr.Read())
{
  //put in a comma / break for the previous item
  Response.Write(",<br>insert into test values(N'"+dr[0]+"', N'"+dr[1]+"')");
}

However, it would be better to just use a StringBuilder to construct the string in memory, and then Response.Write it all at once, like this:

StringBuilder sb = new StringBuilder();    
while (dr.Read())
{
  //put in a comma / break for the previous item
  sb.Append("insert into test values(N'"+dr[0]+"', N'"+dr[1]+"'),<br>");
}
sb.Remove(sb.Length-5,5); // remove the last ,<br>

Response.Write(sb.ToString());