Update record while reading DataReader

Question

I don't understand why this code doesn't update the data table:

SqlCommand cmd = new SqlCommand("Select Count(*) From Utilizatori where NumeUtilizator='"+ usermailtxt +"' and Parola='"+ passtxt +"'", conn);

SqlDataReader sdr = cmd.ExecuteReader();

if (sdr.Read()) 
{
    DateTime dateTime = DateTime.Now;

    SqlCommand cmmd = new SqlCommand("Update Utilizatori Set UltimaUtilizare = '"+ dateTime + "' where IdUtilizatori='"+sdr[0]+"' ", conn);
    cmmd.ExecuteNonQuery();
}

Here I tried making something like "last seen on dd/MM/yyyy at hh:mm", updating a data table after successfully logging in (the email is useless):

this is the data table

Idutilizatori	NumeUtilicator	Parola	EmailUtilizator	UltimaUtilizare
1	bruh	admin	[email protected]	4/11/2024 12:40
2	admin	admin	asd	4/11/2024 1:12
3	NULL	NULL	NULL	4/11/2024 1:11

Basically, I want to search by UserId, and it didn't update anything. Even when I changed it to user name (NumeUtilizator), the result was the same.

SqlCommand cmmd = new SqlCommand("Update Utilizatori Set UltimaUtilizare = '"+ dateTime + "' where NumeUtilizator=@usertxt ", conn);

Not even when I tried using parameters:

SqlCommand cmmd = new SqlCommand("Update Utilizatori Set UltimaUtilizare = '"+ dateTime + "' where NumeUtilizator=@usertxt ", conn);

cmmd.Parameters.AddWithValue("@usertxt", usermailtxt.Text);
cmmd.ExecuteNonQuery();

So, how do I update by ID?

Answer 1

I think you can't use the same connection for updating, while the reader is open. You could try using a second connection for the update or close the reader before executing the update.

Reference

This may be a duplicate to C# While reading data with DataReader cannot update same record