VS2005 C# error message 1)"starting a second loop on a single thread is not a valid operation" or 2)"Child list for field Authors cannot be created" (many-to-many relationship)
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VS2005 C# This is my first C# project. I have books, authors and a bkauthlink table linking the other two tables creating a many-to-many relationship. I get an error in Program.cs: one is a problem with the way I'm calling my main form; the other error may mean I have program.cs correct but there's a problem in my data class--specifically with the data relations involving a many-to-many relationship. Program.cs class: namespace BooksAuthors { static class Program { // The main entry point for the application. [STAThread] static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); //error re single thread if use this //"Starting a second message loop on a single thread is not a valid operation. //Use Form.ShowDialog instead." //Application.Run(new BooksAuthors.MainForm()); //error "Child list for field Authors cannot be created" Application.Run(new MainForm()); } } } Here's the class for the data: namespace BooksAuthors { internal class ClassDataHandling { public void MainDataClass() { string connString = @"Server=RHOADESD;Integrated Security=True;" + "Database=BOOKS"; SqlConnection conn = new SqlConnection(connString); SqlDataAdapter booksAdapter = new SqlDataAdapter( "Select * from books", conn); SqlDataAdapter bkauthlinkAdapter = new SqlDataAdapter( "Select * from bkauthlink", conn); SqlDataAdapter authorAdapter = new SqlDataAdapter( "Select * from authors", conn); conn.Open(); DataSet BookAuthDataSet = new DataSet("BookAuthors"); booksAdapter.Fill(BookAuthDataSet, "books"); bkauthlinkAdapter.Fill(BookAuthDataSet, "bkauthlink"); authorAdapter.Fill(BookAuthDataSet, "authors"); conn.Close(); DataRelation book = BookAuthDataSet.Relations.Add( "BookRel", BookAuthDataSet.Tables["books"].Columns["booksID"], BookAuthDataSet.Tables["bkauthlink"].Columns["booksID"]); DataRelation author = BookAuthDataSet.Relations.Add( "AuthRel", BookAuthDataSet.Tables["authors"].Columns["authorsID"], BookAuthDataSet.Tables["bkauthlink"].Columns["authorsID"]); New to C#
modified on Friday, February 27, 2009 2:31 PM
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VS2005 C# This is my first C# project. I have books, authors and a bkauthlink table linking the other two tables creating a many-to-many relationship. I get an error in Program.cs: one is a problem with the way I'm calling my main form; the other error may mean I have program.cs correct but there's a problem in my data class--specifically with the data relations involving a many-to-many relationship. Program.cs class: namespace BooksAuthors { static class Program { // The main entry point for the application. [STAThread] static void Main() { Application.EnableVisualStyles(); Application.SetCompatibleTextRenderingDefault(false); //error re single thread if use this //"Starting a second message loop on a single thread is not a valid operation. //Use Form.ShowDialog instead." //Application.Run(new BooksAuthors.MainForm()); //error "Child list for field Authors cannot be created" Application.Run(new MainForm()); } } } Here's the class for the data: namespace BooksAuthors { internal class ClassDataHandling { public void MainDataClass() { string connString = @"Server=RHOADESD;Integrated Security=True;" + "Database=BOOKS"; SqlConnection conn = new SqlConnection(connString); SqlDataAdapter booksAdapter = new SqlDataAdapter( "Select * from books", conn); SqlDataAdapter bkauthlinkAdapter = new SqlDataAdapter( "Select * from bkauthlink", conn); SqlDataAdapter authorAdapter = new SqlDataAdapter( "Select * from authors", conn); conn.Open(); DataSet BookAuthDataSet = new DataSet("BookAuthors"); booksAdapter.Fill(BookAuthDataSet, "books"); bkauthlinkAdapter.Fill(BookAuthDataSet, "bkauthlink"); authorAdapter.Fill(BookAuthDataSet, "authors"); conn.Close(); DataRelation book = BookAuthDataSet.Relations.Add( "BookRel", BookAuthDataSet.Tables["books"].Columns["booksID"], BookAuthDataSet.Tables["bkauthlink"].Columns["booksID"]); DataRelation author = BookAuthDataSet.Relations.Add( "AuthRel", BookAuthDataSet.Tables["authors"].Columns["authorsID"], BookAuthDataSet.Tables["bkauthlink"].Columns["authorsID"]); New to C#
modified on Friday, February 27, 2009 2:31 PM
Welcome to code project :beer: It seems you have made some assumptions about how to use these forums. I suggest you take a look at the first message in this forum. Also click here[^] to read some forum guidelines. Then keep in mind that you are asking people to help you for free. So take your time and attempt to provide complete concise information. For example your subject says "error message" but you did not seem to post the error message so no one here knows what it says. Secondly you posted code that is likely not relevant which means you did not take the time to formulate your post to optimize the time people will have to apply FOR FREE to help you.
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Welcome to code project :beer: It seems you have made some assumptions about how to use these forums. I suggest you take a look at the first message in this forum. Also click here[^] to read some forum guidelines. Then keep in mind that you are asking people to help you for free. So take your time and attempt to provide complete concise information. For example your subject says "error message" but you did not seem to post the error message so no one here knows what it says. Secondly you posted code that is likely not relevant which means you did not take the time to formulate your post to optimize the time people will have to apply FOR FREE to help you.
I'm sorry. I have Googled for a couple days now and tried various things. This is my first C# project, I am teaching myself, and I have a many-to-many relationship between books and authors tables (linked by bkauthlink table) in SQL Server. No doubt it is not a good first project but it is what I have (a problem I need solved). There is not a great deal published on this scenario or I am googling the wrong terms. I have googled my error messages as well. And I did read how to post but have added to the subject and the body. I noted in the body of the code where the issues(s) happened but it seemed like a humongous subject line. I have one of two errors depending on how I call the form in my project. Any help would be greatly appreciated and if it were pleasant, all the more so. Thanks!
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I'm sorry. I have Googled for a couple days now and tried various things. This is my first C# project, I am teaching myself, and I have a many-to-many relationship between books and authors tables (linked by bkauthlink table) in SQL Server. No doubt it is not a good first project but it is what I have (a problem I need solved). There is not a great deal published on this scenario or I am googling the wrong terms. I have googled my error messages as well. And I did read how to post but have added to the subject and the body. I noted in the body of the code where the issues(s) happened but it seemed like a humongous subject line. I have one of two errors depending on how I call the form in my project. Any help would be greatly appreciated and if it were pleasant, all the more so. Thanks!
Diana Rhoades wrote:
I am teaching myself
Diana Rhoades wrote:
No doubt it is not a good first project but it is what I have
If you are teaching yourself then you should be able to pull the plug on a project that is not a good first project and start a new one.
Diana Rhoades wrote:
There is not a great deal published on this scenario or I am googling the wrong terms.
There is a great deal published on all the topics involved in your scenario. However probably not one that matches exactly your combination of all the issues and technologies involved. This is why a developer needs to understand the basics of all the different technologies they need to use in a project, so that they are capable of integrating them all to accomplish the goals of the project. Here is an excerpt from an Allen Holub article, where he discusses what things and why they are important for developers to know. (link to article)[^]
As far as I can tell, it’s because many so-called programmers just don’t know how to build a compiler. I really don’t have much patience for this sort of thing. To my mind, there is a minimum set of topics with which you have to be conversant to call yourself a professional programmer. If you don’t know these things, you’re a dilettante. This list includes a deep understanding of data structures and key algorithms, a little math (set theory, logic, a little statistics), mastery of analysis-and-design techniques, both process (e.g., RUP or XP) and structure (e.g., design patterns), and database structure and use (e.g., SQL). You also need to know how the hardware works. You need this stuff even if you’re not actually using it in your work, because no matter what you’re doing, knowing this material will make your work better. How could you possibly decide which of Java’s Collection classes to use in a particular situation if you don’t know how those classes work under the covers, for example? Knowing how to build a compiler is certainly one of the skills on this need-to-know list. Compilers are fundamental to what we do every day as a programmer. Knowing how the compiler works will let you make intelligent decisions about