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POCount how many columns 'is not null' for each row and put that information into another column
 

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  1. POCount how many columns 'is not null' for each row and put that information into another column
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    <p>I am new to SQL and have started a kind of test project to get my hands dirty working with SQL and C#. I have been using VS2012's database wizards to set everything up. So here's the rundown of my setup.</p> <p>SQL CE table named <code>ACDTable</code> and it is connected to my C# project by a dataset <code>dataSet1</code> and a table adapter <code>dataTableAdapter</code></p> <p><code>ACDTable</code> has 22 columns and what I am trying to do is for each row that has a value (is not null) for each column I specify it adds one to a counter and then adds the sum to another column I specify.</p> <p>Essentially I need to find how many columns are not null for each row and turn that number into something usable in C#.</p> <p>Example:</p> <pre><code> |Col1 | Col2 | Col3| Col4| Col5| | | | | | | | x | x | | x | 3 | | | x | x | | 2 | | x | | | | 1 | </code></pre> <p>I am using the example <a href="https://stackoverflow.com/questions/18193365/count-of-non-null-columns-in-each-row">Count of non-null columns in each row</a> and it does work great if I just run it as a query via SQL. </p> <p>The example I am using:</p> <pre><code>SELECT Col1, Col2, Col3, Col4, CASE WHEN Col1 IS NOT NULL THEN 1 ELSE 0 END + CASE WHEN Col2 IS NOT NULL THEN 1 ELSE 0 END + CASE WHEN Col3 IS NOT NULL THEN 1 ELSE 0 END + CASE WHEN Col4 IS NOT NULL THEN 1 ELSE 0 END AS Col5 FROM ACDTable </code></pre> <p>The problem I am running into is when I use Visual Studio to create a method based on this Query and I try to get the values of <code>Col5</code> via that method I am getting a NullDB exception. If I run the debugger and look at the table after I have called the method the <code>Col5</code> is completely null. I have a feeling the problem is the query itself is not actually changing the 5th column but my inexperience with SQL is showing and I cannot figure out the correct syntax to fix this.</p> <p><strong>Fixed typo where I had Col5 in the SELECT list</strong></p> <p><strong>Edit to show the code I am using</strong></p> <p>The method itself is the one generated by Visual Studio using the Add Query option in the Table Adapter. It is if I understand correctly supposed to run the above query and then put the values into <code>Col5</code> for me. I then just want to to see those values represented in a richtextbox using</p> <pre><code>GetTotals(); //The Generated method from VS that runs my query var totals = from p in dataTable select p.Col5; foreach (var total in totals) { testTextBox.Text = total } </code></pre>
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    1. USNabbic
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    1. COYou are returning 2 columns named Col5?
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      1. USRalf
    2. COIs this a sql question or Linq-To-DataSet question? So can you change the sql or do you want to get it in memory on an existing DataTable? That are completely different approaches and questions.
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      1. USTim Schmelter
    3. CO@Ralf Hmm no should only be 1 Col5. Col5 is like the Totals column that represents the sum of the non-null columns prior to 5.
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      1. USNabbic
 

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