I'm wondering if anyone is able to shed light on why this won't work for me. I am trying to run a standard sql query in my ASP MVC application and mostly this is fine. But for some reason when I try to use the 'like' predicate with wildcards it doesn't return any results, it's as if it is using the ? parameter as a value instead of populating with the search value. For example :-
This query returns results without the wildcard included.
SELECT * FROM LOCATIONS L INNER JOIN ITEMDETAILS IT ON IT.LOCNUMBER = L.LOCNUMBER WHERE L.CLIENTNUMBER = ? AND IT.[DESC] LIKE ?;
This query doesn't return any results when I add the wildcard around the parameter value, but no idea why?
SELECT * FROM LOCATIONS L INNER JOIN ITEMDETAILS IT ON IT.LOCNUMBER = L.LOCNUMBER WHERE L.CLIENTNUMBER = ? AND IT.[DESC] LIKE '%?%';
Thanks for your help as always.
Related
I'm trying to convert this SQL code to linq sql. But I don't understand even with the doc... someone can help me please ?
select prcleunique, LibelleProjet, from projet a
where eqcleunique in (select EqCleunique from Compo where uscleunique = '{0}')
and (a.socleunique in (select socleunique from utilisat where uscleunique = '{0}') or a.socleunique is null)
and a.archive = 2 order by LibelleProjet", idUtilisateur);
Those nested sql queries can be broken down nicely in Linq. Every time you have a select have a seperate linq query:
var clause1 = from row in _db.Compo where uscleunique == '{0}' select EqCleunique;
Then use the clauses in the last query
var result = from row in _db.project where clause1.Contains(row.eqcleunique) select row.whatever;
I hope this example is enough to get you started.
I need to process the query at the bottom of this post in C#. The query works, but I don't know how to use it in EF6. I used a method and a viewmodel for it (variable query = the query below). But when it encounters null values in the OUTER JOIN, int32 cant accept this value when calling .toList(). What's the best way to deal with it?
var result = context.Database.SqlQuery<TourQueryViewModel>(query);
var reslist = result.ToList();
I tried my first steps with LINQ, but I dont get it how to translate into LINQ itself or the query-methods, that are equivalent to it. So I am hoping for your help.
SELECT toursdata.TourId AS TourId, toursdata.Tourname AS Tourname,toursdata.Tourdate Tourdate,
toursdata.VehicleId AS VehicleId, toursdata.VehicleName AS VehicleName, toursdata.LicenseNumber AS LicenseNumber,
Employees.EmployeeId AS EmployeeId, Employees.Gender AS Gender, Employees.Forename AS Forename, Employees.Surname AS Surname
FROM (
SELECT te.TourId, te.Tourname, te.Tourdate,
Vehicles.VehicleId, Vehicles.VehicleName, Vehicles.LicenseNumber,
TourEmployees.EmployeeId
FROM TourEmployees RIGHT OUTER JOIN Tours AS te ON TourEmployees.TourId = te.TourId,
Tours AS tv INNER JOIN Vehicles ON tv.VehicleId = Vehicles.VehicleId
WHERE tv.TourId = te.TourId
) toursdata
LEFT OUTER JOIN Employees ON toursdata.EmployeeId = Employees.EmployeeId
To eliminate the null problem, I changed the data type of the corresponding entity-attribute to a nullable-type
int turned to int?.
Didnt know about that language feature.
I'm still a novice at SQL and I need to run a report which JOINs 3 tables. The third table has duplicates of fields I need. So I tried to join with a distinct option but hat didn't work. Can anyone suggest the right code I could use?
My Code looks like this:
SELECT
C.CUSTOMER_CODE
, MS.SALESMAN_NAME
, SUM(C.REVENUE_AMT)
FROM C_REVENUE_ANALYSIS C
JOIN M_CUSTOMER MC ON C.CUSTOMER_CODE = MC.CUSTOMER_CODE
/* This following JOIN is the issue. */
JOIN M_SALESMAN MS ON MC.SALESMAN_CODE = (SELECT SALESMAN_CODE FROM M_SALESMAN WHERE COMP_CODE = '00')
WHERE REVENUE_DATE >= :from_date
AND REVENUE_DATE <= :to_date
GROUP BY C.CUSTOMER_CODE, MS.SALESMAN_NAME
I also tried a different variation to get a DISTINCT.
/* I also tried this variation to get a distinct */
JOIN M_SALESMAN MS ON MC.SALESMAN_CODE =
(SELECT distinct(SALESMAN_CODE) FROM M_SALESMAN)
Please can anyone help? I would truly appreciate it.
Thanks in advance.
select distinct
c.customer_code,
ms.salesman_code,
SUM(c.revenue_amt)
FROM
c_revenue c,
m_customer mc,
m_salesman ms
where
c.customer_code = mc.customer_code
AND mc.salesman_code = ms.salesman_code
AND ms.comp_code = '00'
AND Revenue_Date BETWEEN (from_date AND to_date)
group by
c.customer_code, ms.salesman_name
The above will return you any distinct combination of Customer Code, Salesman Code and SUM of Revenue Amount where the c.CustomerCode matches an mc.customer_code AND that same mc record matches an ms.salesman_code AND that ms record has a comp_code of '00' AND the Revenue_Date is between the from and to variables. Then, the whole result will be grouped by customer code and salesman name; the only thing that will cause duplicates to appear is if the SUM(revenue) is somehow different.
To explain, if you're just doing a straight JOIN, you don't need the JOIN keywords. I find it tends to convolute things; you only need them if you're doing an "odd" join, like an LEFT/RIGHT join. I don't know your data model so the above MIGHT still return duplicates but, if so, let me know.
How can I get F# to do the equivalent of
select a.id, avg(case when a.score = b.score then 1.0 else 0.0 end)
from table1 a join table2 b on a.id = b.id and a.date = b.date
group by a.id
in a query expression? I've come up with
query {
for a in db.table1 do
join b in db.table2 on ((a.id, a.date) = (b.id, b.date))
groupBy a.id into g
select (g.Key, ???) }
but I can't figure out what to insert into "???". To make things worse, the "score" column can be null, which complicates the math.
Alternatively, is there an easier way to do this? I'm not very familiar with .NET database access. Ideally, I'd just give it a block of SQL, it would parse it, and spit back some typed data. As it is, trying to figure out the not-SQL syntax for straightforward SQL is pretty frustrating.
The translation to SQL can generally deal better with C#-style LINQ operations than with native F# functions. So it is easier to go with Select and Average extension methods than with standard F# functions like Seq.map and Seq.average.
I tried writing a similar grouping using a sample Northwind database - I did not find nice tables to join, but the following does basic aggregation with CASE and works fine:
open System.Linq
query {
for p in db.Products do
groupBy p.CategoryID.Value into g
select (g.Key, g.Select(fun a ->
if a.UnitPrice.Value > 10.0M then 1.0 else 0.0).Average()) }
|> Array.ofSeq
It generates a query that is a bit more complicated, but looks right (and uses CASE on the SQL side). You can see that by setting db.DataContext.Log <- System.Console.Out.
Another thing that should generally work would be to use nested query, but I have not tried that.
Some years now, but never too late? Is this of any help? In particular, note the use of FirstOrDefault. Sorry for the Norwegian names, but that's not important. The "x" demonstrates access to the first table.
type Result3 = { Aarsak: int; Beskrivelse: string; Antall: int; Varighet: Nullable<int> }
let query3 = query {
for stopptid in dc.StoppTider do
where (stopptid.DatoS = datoS && stopptid.SkiftNr = skiftNr)
groupBy stopptid.Aarsak into g
join stoppaarsak in dc.StoppAarsak on (g.FirstOrDefault().Aarsak.ToString() = stoppaarsak.Nr)
select { Aarsak = g.Key; Beskrivelse = stoppaarsak.Norsk; Antall = g.Count(); Varighet = g.Sum(fun x -> x.Varighet) }
}
I first ended up here when googling. Since it didn't help, I googled equivalent solutions in C#, got a hit on SO, got that to work for my case in C#, then in F#. This is the link:
LINQ: combining join and group by
I have a Custom Query that look like this
self.account.websites.find(:all,:joins => [:group_websites => {:group => :users}],:conditions=>["users.id =?",self])
where self is a User Object
I manage to generate the equivalent SQL for same
Here how it look
sql = "select * from websites INNER JOIN group_websites on group_websites.website_id = websites.id INNER JOIN groups on groups.id = group_websites.group_id INNER JOIN group_users ON (groups.id = group_users.group_id) INNER JOIN users on (users.id = group_users.user_id) where (websites.account_id = #{account_id} AND (users.id = #{user_id}))"
With the decent understanding of SQL and ActiveRecord I assumed that(which most would agree on) the result obtained from above query might take a longer time as compare to result obtained from find_by_sql(sql) one.
But Surprisingly
When I ran the above two
I found the ActiveRecord custom Query leading the way from ActiveRecord "find_by_sql" in term of load time
here are the test result
ActiveRecord Custom Query load time
Website Load (0.9ms)
Website Columns(1.0ms)
find_by_sql load time
Website Load (1.3ms)
Website Columns(1.0ms)
I repeated the test again an again and the result still the came out the same(with Custom Query winning the battle)
I know the difference aren't that big but still I just cant figure out why a normal find_by_sql query is slower than Custom Query
Can Anyone Share a light on this.
Thanks Anyway
Regards
Viren Negi
With the find case, the query is parameterized; this means the database can cache the query plan and will not need to parse and compile the query again.
With the find_by_sql case the entire query is passed to the database as a string. This means there is no caching that the database can do on the structure of the query, and it needs to be parsed and compiled on each occasion.
I think you can test this: try find_by_sql in this way (parameterized):
User.find_by_sql(["select * from websites INNER JOIN group_websites on group_websites.website_id = websites.id INNER JOIN groups on groups.id = group_websites.group_id INNER JOIN group_users ON (groups.id = group_users.group_id) INNER JOIN users on (users.id = group_users.user_id) where (websites.account_id = ? AND (users.id = ?))", account_id, users.id])
Well, the reason is probably quite simple - with custom SQL, the SQL query is sent immediately to db server for execution.
Remember that Ruby is an interpreted language, therefore Rails generates a new SQL query based on the ORM meta language you have used before it can be sent to the actual db server for execution. I would say additional 0.1 ms is the time taken by framework to generate the query.