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POHow can I update a cell value in a dB table, using SQL Server CE and C# (Visual Studio 2010)
 

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  1. POHow can I update a cell value in a dB table, using SQL Server CE and C# (Visual Studio 2010)
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    <p>I'm writing a small application for college, a video rental application. I have no problems reading from the database, but I cannot update the data in the tables. </p> <p>In particular I'm looking to update the cell showing the quantity of a film in stock after someone rents a movie. </p> <p>So far I've been trying this:</p> <pre><code>string updateDVDs = "UPDATE Products SET dvd_quantity = " + product.Quantity + " WHERE title = '"+ product.Name +"';"; cmdUpdateDVDs = new SqlCeCommand(updateDVDs, dBConnection); dBConnection.Open(); cmdUpdateDVDs.ExecuteNonQuery(); dBConnection.Close(); </code></pre> <p>I don't get any errors, but the cell doesn't update in the table. Any help would be greatly appreciated, please let me know if you require further information. </p> <p><strong>UPDATE:</strong> OK, I have some interesting developments, I have updated the code to this:</p> <pre><code>string updateDVDs = "UPDATE Products SET dvd_quantity = " + product.Quantity + " WHERE title = '" + product.Name + "'"; dBConnection = new SqlCeConnection(connectionString); cmdUpdateDVDs = new SqlCeCommand(updateDVDs, dBConnection); cmdUpdateDVDs.Connection.Open(); int rows = cmdUpdateDVDs.ExecuteNonQuery(); dBConnection.Close(); </code></pre> <p>From what I can tell looking on MSDN both methods are valid, but this second one seems to be working. Now the weird bit, I rent the movie 'Die Hard', it all goes swimmingly, I get these results:</p> <p><img src="https://i.stack.imgur.com/KYhcl.png" alt="Database updated"></p> <p>All good, There is no way back from this point, so I quit the application and start again. I go to rent 'Die Hard' a second time to confirm, and, success!! the new reading on the DVD quantity is 0 as expected: <img src="https://i.stack.imgur.com/9nGQN.png" alt="DVD quantity successfully updated!"> </p> <p>But, when I open the Product table in Visual Studio the original values are still there: <img src="https://i.stack.imgur.com/AqHbp.png" alt="In Visual Studio the table hasn&#39;t updated"></p> <p>Not only that, but when I run the application again after opening the table in Visual Studio the DVD quantities are reset to the original values and the updated values are gone. </p> <p>Am I missing something simple here? I've tried refreshing the table, it doesn't make any difference. As long as I don't open the table in Visual Studio the application behaves as expected, no matter how many times I run it, the values update as expected, until I open the table itself. </p>
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    1. CONone of my string queries have the ; at the end. For instance: `const string query = "SELECT * FROM dailyreport";` is my query.
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    2. COI should suggest using a ORM like EF or Linq2SQL to talk against a database instead of using queries in your code. check out this [link](http://researchaholic.com/2012/02/10/how-to-get-entity-framework-to-talk-to-sql-ce-4/)
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      1. POHow can I update a cell value in a dB table, using SQL Server CE and C# (Visual Studio 2010)
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    3. COThanks Prayos, I changed my statement, it didn't make a difference.
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      1. POHow can I update a cell value in a dB table, using SQL Server CE and C# (Visual Studio 2010)
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