how to get values from SqlDataReader to forloop execution? - c#-4.0

Question

Here I coding for get each and every StudyUID(as string) from database to SqlDataReader,but i need to know how the reader value call to forloop execution.
Get to read each and every StudyUID for execution.Here is the code :.
public void automaticreport()
{
//string autsdyid="";
SqlConnection con = new SqlConnection(constr);
con.Open();
string autoquery = "Select StudyUID From StudyTable Where status='2'";
SqlCommand cmd = new SqlCommand(autoquery, con);
SqlDataReader rdr = cmd.ExecuteReader();
for()
{
//how to call each StudyUId from database through for loop
if (!this.reportchk)
{
Reportnew cf = new Reportnew();
ThreadPool.QueueUserWorkItem((WaitCallback)(o => cf.ReportRetrive(this, autsdyid, true)));
}
else
{
int num = (int)System.Windows.Forms.MessageBox.Show("Reports checking in progress, Please wait sometime and try again later", "OPTICS", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
}
con.Close();
}

Answer 1

Like #R.T and others have mentioned you can use the Read method on the data reader. Looking at your sample code you might want to refactor it slightly to meet more of the SOLID principles and make sure you're not leaking database connections
Here's an example of code that has been refactored a bit.
public void automaticreport()
{
foreach (var autsdyid in LoadStudyIdentifiers())
{
if (!this.reportchk)
{
Reportnew cf = new Reportnew();
ThreadPool.QueueUserWorkItem((WaitCallback)(o => cf.ReportRetrive(this, autsdyid, true)));
}
else
{
int num = (int)System.Windows.Forms.MessageBox.Show("Reports checking in progress, Please wait sometime and try again later", "OPTICS", MessageBoxButtons.OK, MessageBoxIcon.Asterisk);
}
}
}
private string[] LoadStudyIdentifiers()
{
var results = new List<string>();
// adding a using statement will close the database connection if there are any errors
// avoiding consuming the database connection pool
using (var con = new SqlConnection(constr))
{
conn.Open();
var autoquery = "Select StudyUID From StudyTable Where status='2'";
using (var cmd = new SqlCommand(autoquery, con))
{
SqlDataReader rdr = cmd.ExecuteReader();
while(rdr.Read())
{
results.Add(rdr.GetString(rdr.GetOrdinal("StudyUID")));
}
}
}
return results.ToArray();
}
Note: I wrote this in notepad so there is no guarantee it will compile but should give an indication as to how you could refactor your code.

Answer 2

if (rdr.HasRows)
{
while (rdr.Read())
{
Console.WriteLine(rdr.getString("columnName"));
}
}

Answer 3

You can use something like:
while (reader.Read())
{
string value = reader.getString("columnName");
}

Answer 4

You may use the while loop like this:
while (rdr.Read())
{
string s = rdr.GetString(rdr.GetOrdinal("Column"));
//Apply logic to retrieve here
}