Simple implementation of a crosstab 2: Using a front-end program to implement

The previous article introduces the simple implementation of a crosstab 1: Using stored procedures, which are taken in front of the program implementation.
Implementation essentials:
1. Read all target scores (flatscroretable)
2. Extract test time (not duplicates) from the target score as a list header for the cross table
3. Extract the test subjects from the target score (not duplicates) as the row header of the crosstab table
4. A DataTable (Crossscroretable) is built dynamically based on 2, which has an account column, a number of exam time columns, and other information.
5. Write the test account in 3 to the DataTable
6. Read score value from flatscroretable fill in crossscroretable corresponding cell
Description: Easy to understand, here the crosstab crossscroretable imagined as an Excel table, the column name as the list header, the account name as the row header.

Main code:
void Loadscoredata ()
{
Read all the grades of the specified student #region read all the results of the specified student
string stuname = Drpstu.selectedvalue;
String connstr = "server=.;D Atabase=demolib; Uid=sa ";
String sql = "Select Subjectname, Studentname, Scorevalue, examdate from t_score WHERE studentname = @StuName";
DataSet ds = new DataSet ();
SqlDataAdapter da = new SqlDataAdapter (SQL, CONNSTR);
Da.SelectCommand.CommandType = CommandType.Text;
Da. SELECTCOMMAND.PARAMETERS.ADD ("@StuName", stuname);
Da. Fill (ds, "Flatscore");
#endregion Read all the results of a specified student

DataTable flatscoretable = ds. Tables[0];
DataView Flatscoreview = new DataView (flatscoretable);
Read Account list, excluding duplicates
DataTable subjectlist;
. NET 2 Using the ToTable method supported by DataView
Subjectlist = flatscoreview.totable ("Subjectlist", True, "subjectname");
Subjectlist = selectdistinct (flatscoretable, "Subjectlist", True, "subjectname");
Read the test time list, excluding duplicates
. NET 2
DataTable examdatelist;
. NET 2 Using the ToTable method supported by DataView
Examdatelist = flatscoreview.totable ("Examdatelist", True, "examdate");
Examdatelist = selectdistinct (flatscoretable, "Examdatelist", True, "examdate");

Create a crosstab #region create a crosstab table
DataTable crossscoretable = new DataTable ();

Constructing table Schema #region table schema
Account columns
CROSSSCORETABLE.COLUMNS.ADD ("Subject", typeof (String));
Test Time column, with time as column name
foreach (DataRow r in Examdatelist.rows) {
CROSSSCORETABLE.COLUMNS.ADD ((DateTime) r[0]). ToString ("yyyy m-month DD Day"), typeof (String));
}
#endregion Construct Table Schema

Read and write data from the score table read and write data from the #region
DataColumnCollection cols = crossscoretable.columns;
By first account (row) after time (column) traversal
foreach (DataRow r in Subjectlist.rows) {
DataRow NewRow = Crossscoretable.newrow ();
Subjects
Newrow[0] = r[0];
Score, traversal time
for (int i=1; i< cols. Count; i++) {
Returns the results of a specified account and a specified test
eg. "Subjectname= ' Sun Guang ' and examdate= ' 2007-5-19 '"
                flatscoreview.rowfilter =<