Query does not return all data from database - sql-server

Question

I have a C# 4.0 WinForms App using SQL Server 2012 database.
On one of my forms, I select a range of dates from a MonthCalendar.
In a query using a SqlDataAdapter, the query should return 4-names of people from a table.
After filling the DataTable, the "for" loop successfully pulls the first name.
On the next iteration, it also pulls the 2nd person's name from the table.
However, on the 3rd iteration, it again pulls the 2nd person's name and does not retrieve the remaining 2-names.
Using SSMS, I can see all 4-names of the people I'm querying. If I use the query below in SSMS, I again get all 4-names.
Does anyone have an idea why the code below fails to return all 4-names, but returns a previous name?
Here is the code I'm using to query the SQL Server database.
private string ReturnPerson(string dStart, string dEnd)
{
string myPerson = "";
try
{
using (SqlConnection conn = new SqlConnection(#"..."))
{
conn.Open();
using (SqlDataAdapter adap = new SqlDataAdapter("SELECT person, scheduledDate FROM Assignments WHERE scheduledDate BETWEEN #start AND #end ORDER BY scheduledDate ASC", conn))
{
adap.SelectCommand.Parameters.Add("#start", SqlDbType.NVarChar).Value = dStart;
adap.SelectCommand.Parameters.Add("#end", SqlDbType.NVarChar).Value = dEnd;
using (DataTable dt = new DataTable())
{
adap.Fill(dt);
for (int i = 0; i < dt.Rows.Count - 1; i++)
{
DataRow row = dt.Rows[i];
DataRow nextRow = dt.Rows[i + 1];
if (personRowCounter == 0)//rowCounter declared globaly
{
myPerson = row.Field<string>("person").ToString();
personRowCounter++;
return myPerson;
}
else if (personRowCounter > 0)
{
myPerson = nextRow.Field<string>("person").ToString();
personRowCounter++;
return myPerson;
}
}
}
}
}
}
catch (SqlException ex) { MessageBox.Show(ex.Message); }
catch (System.Exception ex) { MessageBox.Show(ex.Message); }
return myPerson;
}

Answer 1

If you start with personRowCounter =0
Then the first call will return row 0 as personRowCounter = 0 and i = 0 and it will set personRowCounter = 1
Then the next call will return row 1 as personRowCounter > 0 and i= 0 and it will set personRowCounter = 1
And all calls after that will return row 1 as personRowCounter > 0 and the loop always starts from 0

Answer 2

I'm not sure what you're intent is here. But, I believe that the problem lies with
DataRow nextRow = dt.Rows[i + 1];
That will throw an exception when i is pointing to the last row. Because [i + 1] will index beyond the end of dt.rows.

Answer 3

Based on the comments above, I've figured out the solution. I needed to adjust the DataRow rows, as per below. This allowed me to pull in the remaining data.
private string ReturnPerson(string dStart, string dEnd)
{
string myPerson = "";
try
{
using (SqlConnection conn = new SqlConnection(#"..."))
conn.Open();
using (SqlDataAdapter adap = new SqlDataAdapter("SELECT person, scheduledDate FROM Assignments WHERE scheduledDate BETWEEN #start AND #end ORDER BY scheduledDate ASC", conn))
{
adap.SelectCommand.Parameters.Add("#start", SqlDbType.NVarChar).Value = dStart;
adap.SelectCommand.Parameters.Add("#end", SqlDbType.NVarChar).Value = dEnd;
using (DataTable dt = new DataTable())
{
adap.Fill(dt);
for (int i = 0; i < dt.Rows.Count - 1; i++)
{
DataRow row0 = dt.Rows[i];
DataRow row1 = dt.Rows[i + 1];
DataRow row2 = dt.Rows[i + 2];
DataRow row3 = dt.Rows[i + 3];
if (dt.Rows.Count > 4)
{
DataRow row4 = dt.Rows[4];
}
if (personRowCounter == 0)//rowCounter declared globaly
{
myPerson = row0.Field<string>("person").ToString();
personRowCounter++;
return myPerson;
}
else if (personRowCounter == 1)
{
myPerson = row1.Field<string>("person").ToString();
personRowCounter++;
return myPerson;
}
else if (personRowCounter == 2)
{
myPerson = row2.Field<string>("person").ToString();
personRowCounter++;
return myPerson;
"etc.";
}
}
}
}
}
catch (SqlException ex) { MessageBox.Show(ex.Message); }
catch (System.Exception ex) { MessageBox.Show(ex.Message); }
return myPerson;
}