Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>If you need to define two types that are <em>mutually recursive</em> (meaning that they can both refer to each other), then you need to place them in a single file and use <code>type ... and ...</code> syntax.</p> <p>In your example, this means that <code>Genre</code> and <code>Album</code> need to be defined like this:</p> <pre><code>// Start a definition block using 'type' as normal type Genre() = let mutable name = String.Empty let mutable albums = [new Album()] member x.Name with get() = name and set (value) = name &lt;- value member x.Albums with get() = albums and set ( value ) = albums &lt;- value // Continue single type definition block using 'and' and Album() = let mutable genre = new Genre() let mutable albumId = 0 let mutable artist = new Artist() member x.Genre with get() = genre and set (value) = genre &lt;- value member x.AlbumId with get() = albumId and set ( value ) = albumId &lt;- value member x.Artist with get() = artist and set ( value ) = artist &lt;- value </code></pre> <p>However, your example is using F# in a very C#-style, so the code does not really look very elegant and it may not give you many of the benefits of functional programming. </p> <p>If I wanted to represent a structure that you're using, then I probably wouldn't add reference to the genre into the <code>Album</code> type. When you place a list of albums inside a <code>Genre</code>, you will always be able to recover the genre when you process the data structure (i.e. to turn it into some other structure, maybe an F# record, that can be passed to data-binding). The beneift of F# is that it lets you write the domain on a few lines, but that works only for functional types. </p> <p>Using discriminated unions with a single case, you can write:</p> <pre><code>// Type aliases to make code more readable type Name = string type AlbumID = int // Simple type definitions to represent the domain type Artist = Artist of Name type Album = Album of AlbumID * Artist type Genre = Genre of Name * Album list </code></pre>
    singulars
    1. This table or related slice is empty.
    1. POF# class reordering Visual Studio
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USTomas Petricek
    1. USTomas Petricek
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POF# class reordering Visual Studio
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTAcceptedByOriginator
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COaah cool, was thinking of trying that, i think i have read that earlier somewhere , kind of forgotten. Many thanks
      singulars
      1. PO
      1. USnetmatrix01
    2. COBut i think we should have a cleaner way of separating types in separate files as well somehow, for now it works , cant complain much, was just thinking for large files might turn out to be tricky.
      singulars
      1. PO
      1. USnetmatrix01
    3. CO@netmatrix01 In a larger project, you would have to use interfaces. Define `Genre` and `Album` as interfaces (in a single file) and then the actual implementation can be separated between larger number of files and refer to these interfaces.
      singulars
      1. PO
      1. USTomas Petricek
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload