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
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
Related
Tired brain - perhaps you can help.
My table has two bit fields:
1) TestedByPCL and
2) TestedBySPC.
Both may = 1.
The user interface has two corresponding check boxes. In the code I convert the checks to int.
int TestedBySPC = SearchSPC ? 1 : 0;
int TestedByPCL = SearchPCL ? 1 : 0;
My WHERE clause looks something like this:
WHERE TestedByPCL = {TestedByPCL.ToString()} AND TestedBySPC = {TestedBySPC.ToString()}
The problem is when only one checkbox is selected I want to return rows having the corresponding field set to 1 or both fields set to 1.
Now when both fields are set to 1 my WHERE clause requires both check boxes to be checked instead of only one.
So, if one checkbox is ticked return records with with that field = 1 , regardless of whether the other field = 1.
Second attempt (I think I've got it now):
WHERE ((TestedByPCL = {chkTestedByPCL.IsChecked} AND TestedBySPC = {chkTestedBySPC.IsChecked})
OR
(TestedByPCL = 1 AND TestedBySPC = 1 AND 1 IN ({chkTestedByPCL.IsChecked}, {chkTestedBySPC.IsChecked})))
Misunderstood the question.
Change the AND to an OR:
WHERE TestedByPCL = {chkTestedByPCL.IsChecked} OR TestedBySPC = {chkTestedBySPC.IsChecked}
Also:
SQL Server does not have a Boolean data type, it's closest option is a bit data type.
The usage of curly brackets suggests using string concatenations to build your where clause. This might not be a big deal when you're handling checkboxes but it's a security risk when handling free text input as it's an open door for SQL injection attacks. Better use parameters whenever you can.
I am making quite the complex thing and I am trying to use tables as variable names cause I have found that lua works with it, that is:
lua
{[{1,2}]="Meep"}
The issue is it is callable, when I do it and try to call it using the same kind of table, it won't find it.
I have tried looking for it and such but I have no clue why it won't do this.
ua
local c = {[{1,2}]="Meep"}
print(c[{1,2}],c)
Do I expect to become but it does not.
"Meep",{[{1,2}]="Meep"}
but what I get is
nil,{[{1,2}]="Meep"}
If I however try
lua
local m={1,2}
local c = {[m]="Meep"}
print(c[m],c)
it becomes the correct one, is there a way to avoid that middle man? After all m=={1,2} will return true.
The problem you have is that tables in lua are represented as references. If you compare two different talbes you are comparing those references. So the equation only gets true if the given tables are exactly the same.
t = { 1, 2, 3 }
t2 = { 1, 2, 3 }
print(t == t) -- true
print(t2 == t) -- false
print(t2 == t2) -- true
Because of this fact, you can pass them in function per reference.
function f(t)
t[1] = 5
end
t2 = { 1 }
f(t2)
print(t2[1]) -- 5
To bypass this behavior, you could (like suggested in comments) serialize the table before using it as a key.
I am using VS2013 with SQL server 2012, VB.net. I am developing a web application.
Let me say before I ask the question that this will probably be extremely simple for this board but I have not been able to find this through googling.
I have an SQL table that holds some data, two columns (settingName (nvarchar) and settingValue (float)). I want to do the following but using LinQ.
SELECT Settingvalue
FROM Settings
WHERE settingName = 'Name1'
I have the following so far in VB.
Dim db As New GMConnectionDataContext
Dim result = From a In db.Settings
Where a.SettingName = "Name1"
Select a.SettingValue
txtEgdon.Text = result
This doesn't work as result is a double but if I add .tostring to result then the output in the text box is the full linq query not the result I am looing for.
I just need to understand this simple query so I can build on it but I just cant get it and any help offered would be great.
This is because your result is an IQueryable and not a single value(even if you expect it to be). This is also why ToString will get you the SQL that will be run against your DB.
You need to get either the First or if you are really sure this would be a single value get Single. The OrDefaults are used in the case that no value is returned so the result will be null.
A Few options:
// You expect 1 to many results and get the first
txtEgdon.Text = result.First().ToString()
// You expect 0 to many results and get the first or null in case of zero results
txtEgdon.Text = result.FirstOrDefault().ToString()
// You expect exactly 1 result and get it (you will get an exception if no results are returned)
txtEgdon.Text = result.Single().ToString()
// You expect exactly 0 or 1 results and get null or the result
txtEgdon.Text = result.SingleOrDefault().ToString()
I would prefer the FirstOrDefault()
I am trying the following code but nhibernate is throwing the following exception:
Expression type 'NhSumExpression' is not supported by this SelectClauseVisitor.
var data =
(
from a in session.Query<Activity>()
where a.Date.Date >= dateFrom.Date && a.Date.Date <= dateTo.Date
group a by new { Date = a.Date.Date, UserId = a.RegisteredUser.ExternalId } into grp
select new ActivityData()
{
UserID = grp.Key.UserId,
Date = grp.Key.Date,
Bet = grp.Sum(a => a.Amount < 0 ? (a.Amount * -1) : 0),
Won = grp.Sum(a => a.Amount > 0 ? (a.Amount) : 0)
}
).ToArray();
I've been looking around and found this answer
But I am not sure what I should use in place of the Projections.Constant being used in that example, and how I should create a group by clause consisting of multiple fields.
It looks like your grouping over multiple columns is correct.
This issue reported in the NHibernate bug tracker is similar: NH-2865 - "Expression type 'NhSumExpression' is not supported by this SelectClauseVisitor."
Problem is that apart from the less-than-helpful error message, it's not really a bug as such. What happens in NH-2865 is that the Sum expression contains something which NHibernate doesn't know how to convert into SQL, which result in this exception being thrown by a later part of the query processing.
So the question is, what does you sum expression contains that NHibernate cannot convert? The thing that jumps to mind is the use of the ternary operator. I believe the NHibernate LINQ provider has support for the ternary operator, but maybe there is something in this particular combination that is problematic.
However, I think your expressions can be written like this instead:
Bet = grp.Sum(a => Math.Min(a.Amount, 0) * -1), // Or Math.Abs() instead of multiplication.
Won = grp.Sum(a => Math.Max(a.Amount, 0))
If that doesn't work, try to use a real simple expression instead, like the following. If that works, we at least know the grouping itself work as expected.
Won = grp.Sum(a => a.Amount)
I'm a newbie at Hibernate so excuse me if some of this is glaringly obvious but it's been a very, very long day. I am trying to create and execute a simple query in Hibernate and Toad/Oracle.
The Toad/Oracle sql reads:
select
count(*)
from
fpps_owner.fee_claim_payment_lines l,
fpps_owner.fee_claim_payments p
where
l.fee_claim_payment_id = p.fee_claim_payment_id and
p.claim_index = 87167895
The above returns 10 records, which is correct
The following Java code returns 0 records, which is NOT correct
String sLinesAvailable =
"select count(*) from " +
"fpps_owner.fee_claim_payment_lines l, fpps_owner.fee_claim_payments p " +
"where " +
"l.fee_claim_payment_id = p.fee_claim_payment_id and p.claim_index = :id";
Query qLinesAvailable = em.createNativeQuery(sLinesAvailable);
qLinesAvailable.setParameter("id", "87167895"); // fails
qLinesAvailable.setParameter("id", 87167895); // fails
List<Object> out = (List<Object>) qLinesAvailable.getResultList();
BigDecimal x = (BigDecimal) out.get(0);
Returns 0 records. Using .getSingleResult() also returns 0 records.
What am I missing here?
Any help would be GREATLY appreciated!
If you are not seeing any malformed query errors, it seems like the parameter is not binding correctly.
To debug, I'd print out that SQL statement the line after you set the parameter. This is the only way you can see the SQL after the parameter is set in order to compare it with Toad.
What does your binding file look like? Maybe you have a different name in there for the ID, so it's not able to find it based on the name. Trying binding with the parameter's order value, just as a test.
This might give some ideas: http://www.mkyong.com/hibernate/hibernate-parameter-binding-examples/
Best of luck! We've all been there :)
What happens when you try:
(Number) query.getSingleResult();
Your query isn't returning a list, but rather just a count.
Good luck.