F＃：如何使用SQL数据源创建Deedle Frame

I am trying to figure what is the best way in F# to create a Deedle Frame, when the data comes from an SQL server. I have tried things like the following.

当数据来自SQL服务器时，我试图找出在F＃中创建Deedle Frame的最佳方法。我尝试过如下的事情。

#I "../packages/Deedle.0.9.12"
#load "Deedle.fsx"

#r "System.dll"
#r "System.Data.dll"
#r "System.Data.Linq"
#r "FSharp.Data.TypeProviders.dll"

open System
open System.Data
open System.Data.Linq
open Microsoft.FSharp.Data.TypeProviders
open Deedle

type dbSchema = SqlDataConnection<"Data Source=server;Initial     Catalog=database;Integrated Security=SSPI;">
let db = dbSchema.GetDataContext()

let fr = db.SomeTable |> Frame.ofRows

and a few other variants. But without luck. I am new to both F# and Deedle for that matter. I can see why the above does not work (the Frame.ofRows is not compatible with the argument) but I don't know what is the best way to proceed (or even how to proceed).

以及其他一些变种。但没有运气。对于F＃和Deedle来说，我是新手。我可以看出上面的原因不起作用（Frame.ofRows与参数不兼容）但我不知道最好的方法是什么（甚至如何继续）。

1 个解决方案

#1

The Frame.ofRows function expects a sequence of series that represent individual rows of the frame. Similarly to Frame.ofColumns, this function is useful if you already have some series objects (or if you are creating everything from scratch). They take input of type seq<'TRowKey * ISeries<'TColKey>>.

Frame.ofRows函数需要一系列表示帧的各个行的系列。与Frame.ofColumns类似，如果您已经有一些系列对象（或者如果您从头开始创建所有内容），则此函数很有用。他们接受seq <'TRowKey * ISeries <'TColKey >>类型的输入。

When you're creating Deedle frame from some .NET data structure, you can use Frame.ofRecords which will work on any sequence and it will use reflection to get the names of the properties (and treat them as column names).

当您从某些.NET数据结构创建Deedle框架时，您可以使用Frame.ofRecords，它将对任何序列起作用，它将使用反射来获取属性的名称（并将它们视为列名称）。

A long explanation, but just a few characters change in your code :-). I tested it with Northwind:

一个很长的解释，但你的代码中只有几个字符改变:-)。我用Northwind测试了它：

type Nwind = SqlDataConnection<"""Data Source=.\SQLExpress;
  Initial Catalog=Northwind;Integrated Security=SSPI;""">
let db = Nwind.GetDataContext()

// Create data frame from Products table (with appropriate column names)
let fr = db.Products |> Frame.ofRecords

The result is:

结果是：

      ProductID ProductName                      SupplierID CategoryID QuantityPerUnit     UnitPrice UnitsInStock UnitsOnOrder ReorderLevel Discontinued OrderDetails                               Categories Suppliers 
0  -> 1         Chai                             1          1          10 boxes x 20 bags  18.0000   39           0            10           False        System.Data.Linq.EntitySet`1[OrderDetails] Categories Suppliers 
1  -> 2         Chang                            1          1          24 - 12 oz bottles  19.0000   17           40           25           False        System.Data.Linq.EntitySet`1[OrderDetails] Categories Suppliers 
2  -> 3         Aniseed Syrup                    1          2          12 - 550 ml bottles 10.0000   13           70           25           False        System.Data.Linq.EntitySet`1[OrderDetails] Categories Suppliers 
3  -> 4         Chef Anton's Cajun Seasoning     2          2          48 - 6 oz jars      22.0000   53           0            0            False        System.Data.Linq.EntitySet`1[OrderDetails] Categories Suppliers 
4  -> 5         Chef Anton's Gumbo Mix           2          2          36 boxes            21.3500   0            0            0            True         System.Data.Linq.EntitySet`1[OrderDetails] Categories Suppliers 
(....)

#1