How can I get integer output from a sql execution using F#

Question

I am new in F#. So that I face some problem in my project.

let getTotalNoOfSmsPerDay (Db cStr) =
 use cmd = new SqlCommandProvider<"select COUNT(id) as NoOfSMS 
 from transport.SmsNotification 
 where CONVERT(date, CreatedOn) = CONVERT(date, GETDATE())
 ",ConnectionString, SingleRow = true>(cStr)
 async {
 let! result = cmd.AsyncExecute()
 return result
 }

This is my Code . I just want a integer number NoOfSMS . But It gives me <Option<int>> How can I solve this?

Thanks in advance

Answer 1

Option represents that nothing may be returned. This is the point where most other languages would return null.

There are a few ways to use the value inside Option. Explore the functions available.

Often what you will do though is to match on the 2 cases ie. Some value was returned or None.

match result with
| Some v -> v
| None -> 0

Here are some links to tutorials I have written on the topics.

Control flow
Pattern matching
Handling no data

• Fatema007: If I want to apply control flow statement in this result it doesn't work. like let! noOfSMSPerday = connection.GetTotalNoOfSmsPerDay if noOfSMSPerday <= 400 then It gives error Type mismatch : 'Async<string>' but given a 'Async<unit>'
• Devon Burriss: If you do not have an else, the return type is unit. Once you have got the int you might want to return from the async CE and just use the value. let n = async { return or return! } depending on what you working with.
• Fatema007: You are right,As I don't write else it gives me unit . Thank you Solved it