与Entity Framework中的3个表连接

debugcn 发表于 Dev

塔利亚

我有一个SQL数据库3个表：Movies，Viewer和Movies_Viewer（=这显示了哪些观众在看到哪部电影）。

客户端将插入Viewer名称和Movie名称，并使用实体框架，我想将其插入到我拥有的3个表中（例如，使用linq），但是我如何知道什么ID使电影和观众将其插入到第三个表中桌子？

我应该插入两个表，然后调用另一个将ID插入第三个表的函数吗？我如何拥有所有数据？

这是我的代码-这样做是错误的吗？

[WebMethod]
public void InsertToDB(string viewerName, string movieName)
{
    InsertToViewerTbl(viewerName);
    InsertToMoviesTbl(movieName);
}

private void InsertToMoviesTbl(string movieName)
{
    var db = new MoviesEntities1();
    var movieNameTbl = new MovieNameTbl();
    movieNameTbl.MovieName = movieName;

    db.AddToMovieNameTbls(movieNameTbl);
    db.SaveChanges();
}

private void InsertToViewerTbl(string viewerName)
{
    var db = new MoviesEntities1();
    var viewerNameTbl = new ViewerNamesTbl();
    viewerNameTbl.ViewerName = viewerName;

    db.AddToViewerNamesTbls(viewerNameTbl);
    db.SaveChanges();
}

玛莉亚

将对象添加到数据库后，您可以只返回对象，例如：

[WebMethod] public void InsertToDB(string viewerName, string movieName) 
{
    var viewer = InsertToViewerTbl(viewerName); 
    var movie = InsertToMoviesTbl(movieName);
    InsertToMovies_Viewer(viewer, movie);
}

private MovieNameTbl InsertToMoviesTbl(string movieName)
{
    var db = new MoviesEntities1();

    var movieNameTbl = new MovieNameTbl();
    movieNameTbl.MovieName = movieName;

    db.AddToMovieNameTbls(movieNameTbl);
    db.SaveChanges();

    return movieNameTbl ;
}

private ViewerNamesTbl InsertToViewerTbl(string viewerName)
{
    var db = new MoviesEntities1();

    var viewerNameTbl = new ViewerNamesTbl();
    viewerNameTbl.ViewerName = viewerName;

    db.AddToViewerNamesTbls(viewerNameTbl);
    db.SaveChanges();

    return viewerNameTbl;
}

private void InsertToMovies_Viewer(ViewerNamesTbl viewer, MovieNameTbl movie)
{
    var db = new MoviesEntities1();

    var movieViewer = new Movies_Viewer();// or however the table is called
    movieViewer.Viewer = viewer; // or however the column is called
    movieViewer.Movie= movie; // or however the column is called

    db.AddToMovies_Viewer(movieViewer);
    db.SaveChanges();
}

但我建议您使用一种方法来执行此操作，这样就不必每次都创建连接，并且每次都保存更改：

[WebMethod] public void InsertToDB(string viewerName, string movieName) 
{
    var db = new MoviesEntities1();

    var movie = new MovieNameTbl();
    movieNameTbl.MovieName = movieName;

    db.AddToMovieNameTbls(movieNameTbl);

    var viewer = new ViewerNamesTbl();
    viewerNameTbl.ViewerName = viewerName;

    db.AddToViewerNamesTbls(viewerNameTbl);

    var movieViewer = new Movies_Viewer();// or however the table is called
    movieViewer.Viewer = viewer; // or however the column is called
    movieViewer.Movie= movie; // or however the column is called

    db.AddToMovies_Viewer(movieViewer);
    db.SaveChanges();
}

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