How do I print student ID card based on datagridview checkbox checked?

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Hi Experts,

I'm very new to .NET (c#) so please help me to solve my issue, I build a simple student project. In this project I created a form to display data from sql database to dgPrintIDCard, I added on more column "cells[0]" for checkbox to dgPrintIDCard then I have a print card button to print the checked row in dgPrintIDCard. It works if I only checked one record but it doesn't work once I have multiple checked. It show multiple crystal report instead of one crystal report show and show all student ID Card regarding to checked rows. Please see my code below.

My purpose is: when I checked only one row, system will show only one card in crystal
When I checked 3 rows, system will show 3 cards in crystal

Your assistance is much appreciated.
Regards,
Cheng

What I have tried:

foreach (DataGridViewRow item in dgPrintIDCard.Rows)
                  {
                      if (item.Cells[0].Value != null)
                      {
                          var stID = item.Cells[1].Value;//Student ID is in cells[1]

                          con = new SqlConnection(cs.DBcon);
                          con.Open();
                          string query = "SELECT * FROM student WHERE s_id = '" + stID + "'"; 
                          cmd = new SqlCommand(query, con);
                          printPreviewGlobalVar.mReport = "prntStudentCard";
                          printPreviewGlobalVar.mSqlstr = query;
                          prntPreview prnt = new prntPreview();
                          prnt.Show(); 

                          this.Close();//close current form
                      }                    
                  }

Posted 30-Jun-19 20:46pm

chenglll

Updated 1-Jul-19 2:39am

v2

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3 solutions

Solution 1

Take out the Close at the end of the if - if you close the form, it will kill the form, and all it's controls - including the DataGridView you are trying to get information from...

Posted 30-Jun-19 21:30pm

OriginalGriff

Comments

chenglll 1-Jul-19 4:28am

I have tried it but still got same result.

Solution 3

Put a conter for each row selected, then you will be able to see each card or print whatever you want to print(it works for me at least)
The way you have that it appears to me that only the first row selected will be printed out

Posted 1-Jul-19 2:40am

JU571C3

Updated 1-Jul-19 2:42am

v2

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Maciej Los · Accepted Answer · 2019-07-01T00:17:00

First of all, please, read carefully OriginalGriff's solution.

Second of all, your query is for one student at time:

C#

"SELECT * FROM student WHERE s_id = '" + stID + "'";

BTW: such of query is sql injection[^] vulnerable!
You have to create a query which accepts several id's to be able to display selected cards. See: IN (Transact-SQL) - SQL Server | Microsoft Docs[^]

C#

StringBuilder sb = new StringBuilder();
foreach (DataGridViewRow item in dgPrintIDCard.Rows)
{
    if (item.Cells[0].Value != null)
    {
        var stID = item.Cells[1].Value.ToString();//Student ID is in cells[1]
        sb.Append($"{stID},");
    }                    
}

string query = $"SELECT * FROM student WHERE s_id IN ({sb.ToString().TrimEnd(',')})"; 
con = new SqlConnection(cs.DBcon);
con.Open();
cmd = new SqlCommand(query, con);
printPreviewGlobalVar.mReport = "prntStudentCard";
printPreviewGlobalVar.mSqlstr = query;
prntPreview prnt = new prntPreview();
prnt.Show(); 
this.Close();//close current form

Note:
I'm using StringBuilder class, because string object is immutable! See: Strings - C# Programming Guide | Microsoft Docs[^]

Links:
StringBuilder Class (System.Text) | Microsoft Docs[^]
String.TrimEnd Method (System) | Microsoft Docs[^]