You can simply check like this:

    return row.Table.Columns.Contains(columnName);


DataTables have that schema info, so check if the Row&#39;s Table&#39;s Columns collection contains the field.

**The Setup:**

- I&#39;m working on a Django application which allows users to create an object in the database and then go back and edit it as much as they desire.
- Django&#39;s admin site keeps a history of the changes made to objects through the admin site.

**The Question:**

- How do I hook my application in to the admin site&#39;s change history so that I can see the history of changes users make to their &quot;content&quot;?

Tying in to Django Admin&#39;s Model History

I&#39;m currently working on a PHP OpenID provider that will work over HTTPS (hence SSL encrypted).  
Is it *wrong* for me to transmit the password as plain text? HTTPS in theory, cannot be intercepted, so I don&#39;t see anything wrong. Or is this unsafe at some level and I&#39;m failing to see this?

Plain text password over HTTPS

How do I check for the existence of a column in a datarow? 

I&#39;m building datatables to organize some data that I&#39;ve already pulled back from the database. Depending on the type of data in each row, I need to create a datatable with different columns.  Then, later on, I want to check and see if the datatable I am looking at has a certain column.

I know I can catch the exception and handle it that way, but I&#39;m curious if there is a property or method on the datarow object that will do this for me?

Here&#39;s how I can do it by catching the exception:

    public static String CheckEmptyDataRowItem(DataRow row, String rowName, String nullValue)
    {
        try
        {
            return row[rowName].ToString();
        }
        catch (System.ArgumentException)
        {
            return nullValue;
        }
    }


ADO.NET DataRow - check for column existence

How do I check for the existence of a column in a datarow?
I'm building datatables to organize some data that I've already pulled back from the database. Depending on the type of data in each row, I need to create a datatable with different columns. Then, later on, I want to check and see if the datatable I am looking at has a certain column.
I know I can catch the exception and handle it that way, but I'm curious if there is a property or method on the datarow object that will do this for me?
Here's how I can do it by catching the exception:
<pre><code class="hljs language-arduino">public static String CheckEmptyDataRowItem(DataRow row, String rowName, String nullValue)
{
 try
 {
 return row[rowName].ToString();
 }
 catch (System.ArgumentException)
 {
 return nullValue;
 }
}
</code></pre>

How do create a DataTable in C#?

I did like this:

     DataTable dt = new DataTable();
     dt.clear();
     dt.Columns.Add(&quot;Name&quot;);
     dt.Columns.Add(&quot;Marks&quot;);

How do I see the structure of DataTable?

Now I want to add *ravi* for `Name` and *500* for `Marks`. How can I do this?


How to create a DataTable in C# and how to add rows?

How can I load a CSV file into a `System.Data.DataTable`, creating the datatable based on the CSV file?

Does the regular ADO.net functionality allow this?

How to read a CSV file into a .NET Datatable

I have a dataset objds. objds contains a table named Table1. Table1 contains column named ProcessName. This ProcessName contains repeated names.So i want to select only distinct names.Is this possible.

      intUniqId[i] = (objds.Tables[0].Rows[i][&quot;ProcessName&quot;].ToString());

How to select distinct rows in a datatable and store into an array

Is there a nice way to convert an IEnumerable to a DataTable?

I could use reflection to get the properties and the values, but that seems a bit inefficient, is there something build-in?

*(I know the examples like: ObtainDataTableFromIEnumerable)*

**EDIT**:  
This [question][1] notified me of a problem handling null values.  
The code I wrote below handles the null values properly.

    public static DataTable ToDataTable&lt;T&gt;(this IEnumerable&lt;T&gt; items) {  
        // Create the result table, and gather all properties of a T        
        DataTable table = new DataTable(typeof(T).Name); 
        PropertyInfo[] props = typeof(T).GetProperties(BindingFlags.Public | BindingFlags.Instance);  

        // Add the properties as columns to the datatable
        foreach (var prop in props) { 
            Type propType = prop.PropertyType; 
 
            // Is it a nullable type? Get the underlying type 
            if (propType.IsGenericType &amp;&amp; propType.GetGenericTypeDefinition().Equals(typeof(Nullable&lt;&gt;))) 
                propType = new NullableConverter(propType).UnderlyingType;  
 
            table.Columns.Add(prop.Name, propType); 
        }  
 
        // Add the property values per T as rows to the datatable
        foreach (var item in items) {  
            var values = new object[props.Length];  
            for (var i = 0; i &lt; props.Length; i++) 
                values[i] = props[i].GetValue(item, null);   
 
            table.Rows.Add(values);  
        } 
 
        return table; 
    } 


  [1]: https://stackoverflow.com/questions/2169157/linq-to-dataset-handling-null-values

Convert IEnumerable to DataTable

I&#39;m just getting started using ADO.NET and DataSets and DataTables. One problem I&#39;m having is it seems pretty hard to tell what values are in the data table when trying to debug.

What are some of the easiest ways of quickly seeing what values have been saved in a DataTable? Is there someway to see the contents in Visual Studio while debugging or is the only option to write the data out to a file?

I&#39;ve created a little utility function that will write a DataTable out to a CSV file. Yet the the resulting CSV file created was cut off. About 3 lines from what should have been the last line in the middle of writing out a System.Guid the file just stops. I can&#39;t tell if this is an issue with my CSV conversion method, or the original population of the DataTable.

**Update**

Forget the last part I just forgot to flush my stream writer.



How to view a DataTable while debugging

I normally set my column size when creating a parameter in ADO.NET.

But what size do I use if the column is of type `VARCHAR(MAX)`?

    cmd.Parameters.Add(&quot;@blah&quot;, SqlDbType.VarChar, ?????).Value = blah;

What size do you use for varchar(MAX) in your parameter declaration?

I just saw this topic: https://stackoverflow.com/questions/2250/datatable-vs-dataset
but it didn&#39;t solve my doubt .. Let me explain better, I was doing connection with database and needed to show the results in a GridView. (I used RecordSet when I worked with VB6 while ago and DataSet is pretty similar to it so was much easier to use DataSet.)
Then a guy told me DataSet wasn&#39;t the best method to do ..

So, should I &#39;learn&#39; DataReader or keep using DataSet ? DataTable ?
What are the pros/cons ?

What&#39;s better: DataSet or DataReader?

        private void button1_Click(object sender, EventArgs e)
        {
            string name;
            name = textBox5.Text;
            SqlConnection con10 = new SqlConnection(&quot;con strn&quot;);
            SqlCommand cmd10 = new SqlCommand(&quot;select * from sumant where username=@name&quot;);
            cmd10.Parameters.AddWithValue(&quot;@name&quot;,name);
            cmd10.Connection = con10;
            cmd10.Connection.Open();//line 7
            SqlDataReader dr = cmd10.ExecuteReader();
        }

        if ( textBox2.Text == dr[2].ToString())
        {
            //do something;
        }

When I debug until line 7, it is OK, but after that `dr` throws an exception:

&gt; Invalid attempt to read when no data is present.

I don&#39;t understand why I&#39;m getting that exception, since I do have data in the table with username=sumant.

Please tell me whether the &#39;if&#39; statement is correct or not. And how do I fix the error?

Invalid attempt to read when no data is present

Trying to parameterize the value of TOP in my sql statement. 

    SELECT TOP @topparam * from table1

    command.Parameters.Add(&quot;@topparam&quot;,SqlDbType.VarChar, 10).Value = somevalue.ToString();

This doesn&#39;t seem to work. Anyone have any suggestions?  
Just to clarify, I don&#39;t want to use stored procedures. 

C# SQL Top as parameter

I want to convert a `DataRow` array into `DataTable` ... What is the simplest way to do this?



Simple way to convert datarow array to datatable

How do I add a new `DataColumn` to a `DataTable` object that already contains data?

PseudoCode

    //call SQL helper class to get initial data 
    DataTable dt = sql.ExecuteDataTable(&quot;sp_MyProc&quot;);
    
    dt.Columns.Add(&quot;NewColumn&quot;, type(System.Int32));
    
    foreach(DataRow row in dr.Rows)
    {
        //need to set value to NewColumn column
    }

How can I add a new column and data to a datatable that already contains data?

I&#39;ve cobbled together a C# program that takes a `.csv` file and writes it to a `DataTable`.  Using this program, I can loop through each row of the `DataTable` and print out the information contained in the row.  The console output looks like this:

    --- Row ---
    Item: 1
    Item: 545
    Item: 507
    Item: 484
    Item: 501

I&#39;d like to print the column name beside each value, as well, so that it looks like this:

    --- Row ---
    Item: 1   Hour
    Item: 545 Day1 KW
    Item: 507 Day2 KW
    Item: 484 Day3 KW
    Item: 501 Day4 KW

Can someone look at my code and tell me what I can add so that the column names will print?  I am very new to C#, so please forgive me if I&#39;ve overlooked something.  

Here is my code:
    
    // Write load_forecast data to datatable.
    DataTable loadDT = new DataTable();
    StreamReader sr = new StreamReader(@&quot;c:\load_forecast.csv&quot;);                      
            
    string[] headers = sr.ReadLine().Split(&#39;,&#39;);
    foreach (string header in headers)
    {
        loadDT.Columns.Add(header); // I&#39;ve added the column headers here.
    }

    while (sr.Peek() &gt; 0)
    {
        DataRow loadDR = loadDT.NewRow();
        loadDR.ItemArray = sr.ReadLine().Split(&#39;,&#39;);
        loadDT.Rows.Add(loadDR);
    }
                        
    foreach (DataRow row in loadDT.Rows)
    {
        Console.WriteLine(&quot;--- Row ---&quot;);
        foreach (var item in row.ItemArray)
        {
            Console.Write(&quot;Item:&quot;);
            Console.WriteLine(item); // Can I add something here to also print the column names?
        }
    }

How do I get column names to print in this C# program?

I want to do something like this:

       private User PopulateUsersList(DataRow row)
            {
                Users user = new Users();
                user.Id = int.Parse(row[&quot;US_ID&quot;].ToString());
                if (row[&quot;US_OTHERFRIEND&quot;] != null)
                {
                    user.OtherFriend = row[&quot;US_OTHERFRIEND&quot;].ToString();
                }
                return user;
            }

However, I get an error saying `US_OTHERFRIEND` does not belong to the table.
I want to simply check if it is not null, then set the value.

Isn&#39;t there a way to do this?



Check if DataRow exists by column name in c#?

I have a problem with a DataRow that I&#39;m really struggling with.

The datarow is read in from an Excel spreadsheet using an OleDbConnection.

If I try to select data from the DataRow using the column name, it returns DBNull even though there is data there.

But it&#39;s not quite that simple.

`datarow.Table.Columns[5].ColumnName` returns &quot;my column&quot;.&lt;br&gt;
`datarow[&quot;my column&quot;]` returns DBNull.&lt;br&gt;
`datarow[5]` returns 500.&lt;br&gt;
`datarow[datarow.Table.Columns[5].ColumnName]` returns DBNull. (just to make sure its not a typo!)

I could just select things from the datarow using the column number, but I dislike doing that since if the column ordering changes, the software will break.

Content Type	Original Author	Original Content on Stackoverflow
Question	Tone	View Question on Stackoverflow
Solution 1 - Datatable	Gaurav	View Answer on Stackoverflow
Solution 2 - Datatable	Wyatt Barnett	View Answer on Stackoverflow

ADO.NET DataRow - check for column existence

Datatable Problem Overview

Datatable Solutions

Solution 1 - Datatable

Solution 2 - Datatable

Plain text password over HTTPS

Tying in to Django Admin's Model History

Attributions