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Looks like the DataGrid is virtualized, so ContainerFromItem returns null for any rows which aren't currently visible.
There are several workarounds suggested in this StackOverflow thread[^].
But as Dave said, it would be better to work with the source directly rather than trying to read the value from the DataGridRow.
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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Why are you getting the data from the DataGrid rows instead of the data source the grid is bound to?
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actually I extracted datas from DataTable. now I want to apply filtering to datagrid and from their I will get the values from current status of datagrid.
what I want is from current filter->get all cell content and store to 1 string with comma delimeter.
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you are right Dave. I dont need to go back and assess datagrid. instead use the data from rowfilter and use datarowview.
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Yes!
The DataGrid should be just for display of the data, not really a container for it.
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Hey, new to programming so be gentle. I am trying to compare two different SQL lists rows with each other using:
SqlCommand value = new SqlCommand("SELECT FROM INNER JOIN ON)
The problem is the FROM function - it will come from 2 different classes in a different common files (to the one I am writing code) and I am not sure i am calling these 2 (separate classes) from the common repository correctly?!
- The first SQL class is public int number1() with the row name name1.
- The second SQL class is public int number2() with the row name name2.
So the SELECT function will be SqlCommand value = new SqlCommand("FROM number1().name1, number2().name2)
So the FROM will go to the common repository and then search for class 1 get the row name one, and search class 2 (same repository) and search for name2? Obciously there is still SELECT INNER JOIN and ON functions but I just want to ensure that the FROM calling is done correctly thank you!!
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The JOIN syntax doesn't look like that:
SELECT a.columnName, b.ColumnName
FROM MyTable a
INNER JOIN MyOtherTable b
ON a.ID == b.MyTableID
I'm really not sure exactly what you are trying to do - your description doesn't make a lot of sense, and we have no access to your data or the relationships between your tables - so start here: SQL Joins[^] and if you can't work it out, give us sample data for your tables, and show what result you expect and why.
Remember that we can't see your screen, access your HDD, or read your mind - we only get exactly what you type to work with.
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
AntiTwitter: @DalekDave is now a follower!
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Thanks that's a good help. But when you are referring to tables I do not know what that would be since -
- I have two diffrent cs files, each file has 2 classes "public 1 ,
public 2). Within those to classes I now have the "myTable a"
and "myTable b". So I first have to refer to the cs. file, than
the class, than the "myTable b" or "myTable a" which im unsure how
to.
So the tables are not created in the same cs file thus when using
SELECT how do i tell c# to go to the class, than the
- When referring to table, you would refer to the SQL table that you
have created i.e. sql file name is "myTable a"?
Thanks for your patience!
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You don't use SQL for classes - SQL is for querying data direct from a DB: it's the source from which you get your data to populate your class instances! And the DB is external to your app, and often managed by a different app altogether: SQL server.
I think you need to sit back and rethink how you are managing data in this app - you don't seem to have quite worked out what gets stored where and how it gets loaded into what, when.
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
AntiTwitter: @DalekDave is now a follower!
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Ok thanks, I will rethink, but you have helped out there, and makes a bit of sense. I am working with the SQL server which makes sense now. Thank you!
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You're welcome!
It's worth considering breaking your app into three parts (either logically or physically using three projects in one solution) to separate what they are doing: Presentation (user interface in and out), Business Logic (the rules and classes that process them), and Data (access to the DB and / or other storage)
That way, you make a more "rigid" interface between the parts of your application, which makes it easier to understand and maintain later.
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
AntiTwitter: @DalekDave is now a follower!
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Thanks I am trying to use the CRUD system with C# and sql, but the syntaxs on what I want to do is too much. I do this as a junior programmer for a company that needs websites, but also a junior physicist trying to develop quantum computing machine learning for data analysis. So you can image all this crap that i have to learn now as a programmer. Much appreciated your help!
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How to create alpha channel in PSD formatted images using C#.net ?
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Most likely by writing some code. And if you have a problem with it the please feel free to post the full details here, so people can try to help.
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I have a problem. I'm trying to get just a company Name from the database and place them in the listbox and when selecting the name the program would show the org. number and notes in text boxes next to the listbox (and later to be able to delete, add and edit companies). I'm already stuck in showing data in the listbox. I'm getting this error "listBoxOrg.Items.Add((tempRow["Name"]));" -->"Argument 1: cannot convert from 'object' to 'string'. I'm pretty new to this so I don't know how to solve it. Is the code all crap or what am I missing? Been wondering also if my database adress is correctly done.. Anyone that can help me out?
This is my code so far:
using System;
using System.Collections;
using System.Collections.Generic;
using System.Diagnostics;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Text;
using System.Configuration;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Threading.Tasks;
namespace Scenario1
{
public partial class companies1 : System.Web.UI.Page
{
public static ArrayList Files = new ArrayList();
protected void Page_Load(object sender, EventArgs e)
{
string str = "Data Source=BIG-BAD-WOLF-CO\\SQLEXPRESS;Integrated Security=True;Connect Timeout=15;Encrypt=False;TrustServerCertificate=True;ApplicationIntent=ReadWrite;MultiSubnetFailover=False";
SqlConnection con = new SqlConnection(str);
string com = "select Name from Companies";
SqlDataAdapter adpt = new SqlDataAdapter(com, con);
DataSet myDataSet = new DataSet();
adpt.Fill(myDataSet, "Companies");
DataTable myDataTable = myDataSet.Tables[0];
DataRow tempRow = null;
foreach (DataRow tempRow_Variable in myDataTable.Rows)
{
tempRow = tempRow_Variable;
listBoxOrg.Items.Add((tempRow["Name"]));
}
}
}
}
modified 1-Dec-20 21:01pm.
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First off, to identify what your problem is, we need to know exactly where in that code the error is being reported. This is not a good question - we cannot work out from that little what you are trying to do. Remember that we can't see your screen, access your HDD, or read your mind - we only get exactly what you type to work with.
Second, your connections string looks OK for yoru dev system - but we have no idea if it works as we have no access to your system to check. But it's unlikely to work in the real world, as it uses integrated security and SQLEXPRESS, and that's unlikely to be the case once you leave your dev machine.
You can try looking here: Simple SQL Connection String Creation[^] which will help you test it.
Third, Connection strings should never be hard coded: you should load them from the web.config file and keep separate web.config files for prod and dev.
Why not just use the DataTable as the DataSource for the ListBox?
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
AntiTwitter: @DalekDave is now a follower!
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Hi! Thanks for answering. Like I said I'm pretty new... actually extremely new to this. Yeah I guess I was pretty unclear with the question. The error shows in the end:
listBoxOrg.Items.Add((tempRow["Name"]));
My Visual Studio 2015 gives that.
This is a work I'm doing for my own "company" and everything I've tried is from educational videos. I thought it just would be a fun thing to know how to do. I've mostly written html and done a bit of java programming. I just can't understand why this works for them in the videos and not for me.
I've tested the connection and it works.
Umm sorry for a stupid question but what do mean with using the DataTable as the DataSource for the ListBox?
modified 1-Dec-20 21:01pm.
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Rather than answering your questions, can I make a suggestion?
"Picking it up as you go" is a bad way to learn anything, particularly when it's as complicated as a new language and / or framework. And trying to learn by looking at Java code and assuming it's the same in C# is just not going to work well at all! For example, ArrayList is fine in Java, but it was supperceded in .NET back in 2005 and certainly shouldn't be used for new projects - the type safe List<T> and other Generic Collections should be.
But learning as you are, you don;t know that, and probably aren't even aware that Generics exist, much less the specifics of List<T>, Queue<T>, and so on.
Get a book - Addison Wesley, Wrox, and MS Press all do excellent ones, and there is also the free Yellow Book[^] which will at least touch the basics.
All of them will introduce you to better ways of handling data that you are currently using, and will make your life a whole load easier in future!
Going on a course is an even better method - if you don't understand something the tutor can try different ways to explain, which books can't.
The worse way to learn is via YouTube videos. Most of them are created by people who have no idea how to make a video, how to teach, and in the majority of cases know little more about the subject that the people watching them ... There are good ones out there, but it's really hard to find the quality items in a sea of dross.
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
AntiTwitter: @DalekDave is now a follower!
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Yeah I guess you're right. It's just pretty sad that there isn't any courses available in where I live. The nearest school that teaches c# and .NET is over an hour away with a car. I guess I have to start reading books. Thanks for the help anyway. 
modified 1-Dec-20 21:01pm.
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You're welcome!
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
AntiTwitter: @DalekDave is now a follower!
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listBoxOrg.Items.Add((tempRow["Name"]));
The message implies that tempRow["Name"] does not return a valid string (and we know it returns an object*), so you could try
listBoxOrg.Items.Add((tempRow["Name"].ToString()));
*as explained in DataRow.Item[String, DataRowVersion] Property[^]
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That actually did work (atleast the debugger won't whine about it anymore) but I'm getting a new error at:
adpt.Fill(myDataSet, "Companies");
"An exception of type 'System.Data.SqlClient.SqlException' occurred in System.Data.dll but was not handled in user code
Additional information: Invalid object name 'Companies'."
I have created a database with two tables: Companies and Stores. So Companies exists.
modified 1-Dec-20 21:01pm.
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Again, documentation... DataAdapter.Fill Method (System.Data.Common) | Microsoft Docs[^]
If you're going to fill a DataSet object, your 'myDataSet', you also need to supply a string next, which you did, but you also have to supply an IDataReader, and a couple of integers.
Don't. You don't need it. Just get rid of the "Companies" string.
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The problem is with your connection string - you haven't specified the Database, so your queries aren't running against the correct database.
SQL Server connection strings - ConnectionStrings.com[^]
"These people looked deep within my soul and assigned me a number based on the order in which I joined."
- Homer
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Hi Guys,
I'm new member with C#, i'm working project with windows form.
My idea is create new label when I click a button, and the label have just created can change location when click and move mouse. And I want save new label and it's location after close app window form. I havent know how to i do this. So Please support for me!
Thanks!
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