出于某种原因,我无法在查询表达式中使用“for”结构。我得到的错误如下所示。我选择的代码过去能够工作 - > "error:仅当计算表达式生成器定义了“For”方法时,才能使用此控件结构"
#r "System.Data.Linq.dll"
#r "FSharp.Data.TypeProviders.dll"
open FSharp.Linq
open FSharp.Data.TypeProviders
[<Literal>]
let connectionString' = @"
data source = ...;
initial catalog = NORTHWND;
Integrated Security = SSPI"
type NorthwndDb =
SqlDataConnection<connectionString', Pluralize = true>
let db' = NorthwndDb.GetDataContext()
let curstomerSortedByCountry =
query { for c in db'.Customers do
sortBy c.Country
select (c.Country, c.CompanyName) }
|> Seq.cache