I am having some issues with trying to figure out the correct way, or syntax, to join/concatenate a series of "name" columns from a separate table into a query.
Currently I am testing in LINQpad using two queries; the first returns all the master data that I use for other background work, and the second is a user-friendly version that I bind to a DGV. The issue comes in when I try to join the Physicians names like I do for a separate combobox.
This is what I have thus far - while it does return the Physician's name, it will NOT return the name if the TITLE field is NULL on the Physicians table.
Dim query1 = (From demog In data_Demogs
From MedHist In data_Demog_MedHists.where(Function(a) demog.ID_Demog = a.ID_Demog).defaultifempty
From BGLAssay In data_Demog_BGLs.where(Function(a) demog.ID_Demog = a.ID_Demog).defaultifempty
Select
demog.ID_Demog,
demog.Last_Name,
demog.First_Name,
demog.ID_Demog_AKA,
demog.DOB,
demog.Gender,
demog.ST_Complete,
demog.LT_Complete,
demog.LT_Due_Date,
demog.ID_Physician,
demog.ID_Reason_For_Call,
demog.Intl_Patient,
demog.Mayo_Patient,
MedHist.ID_Disease_Group,
MedHist.ID_Disease_Type,
BGLAssay.ID_BGL_Assay)
Dim query2 = (From items In query1
From demogAKA In data_Demogs.Where(Function(a) items.ID_Demog = a.ID_Demog_AKA).defaultifempty
From DType In tbl_Disease_Types.Where(Function(a) items.ID_Disease_Type = a.ID_Disease_Type).defaultifempty
From DGroup In tbl_Disease_Groups.Where(Function(a) items.ID_Disease_Group = a.ID_Disease_Group).defaultifempty
From RFC In tbl_Reason_For_Calls.Where(Function(a) items.ID_Reason_For_Call = a.ID_Reason_For_Call).defaultifempty
From Phys In tbl_Physicians.Where(Function(a) items.ID_Physician = a.ID_Physician).defaultifempty
From Title In tbl_Titles.Where(Function(a) Phys.ID_Title = a.ID_Title).defaultifempty
Select
items.ID_Demog,
items.Last_Name,
items.First_Name,
AKA_Name = demogAKA.Last_Name + ", " + demogAKA.First_Name,
items.DOB,
items.Gender,
items.ST_Complete,
items.LT_Complete,
items.LT_Due_Date,
DType.Disease_Type_Abr,
DGroup.Disease_Group_Name,
RFC.Reason_For_Call,
items.ID_Physician,
Phys_Name = Phys.Last_Name + ", " + Phys.First_Name + ", " + Title.Title
).distinct
console.writeline(Query2)
This is the currently query I for a combobox that DOES bring back all names, joining those names even if a field is NULL.
Dim Phys = (From e In tbl_Physicians
Group Join f In tbl_Titles On e.ID_Title Equals f.ID_Title
Into Matched = Group
From m In Matched.DefaultIfEmpty()
Select e.ID_Physician,
e.Last_Name,
e.First_Name,
e.Middle_Initial,
m.Title
).ToArray().Select(Function(item) New With {
.ID = item.ID_Physician,
.Phys_Name = (String.Join(", ",
String.Join(",",
New String() {item.Last_Name, item.First_Name, item.Title}).Split(
New Char() {","}, System.StringSplitOptions.RemoveEmptyEntries)))
})
Console.writeline(Phys)
When I try to add a third query to return just the Physician's name, and join that to the final query, I get the following error:
Local sequence cannot be used in LINQ to SQL implementations of query operators except the Contains operator.
'Query 1 removed to save space
Dim PhysNames = (From e In tbl_Physicians
Group Join f In tbl_Titles On e.ID_Title Equals f.ID_Title
Into Matched = Group
From m In Matched.DefaultIfEmpty()
Select e.ID_Physician,
e.Last_Name,
e.First_Name,
e.Middle_Initial,
m.Title
).ToArray().Select(Function(item) New With {
.ID = item.ID_Physician,
.Phys_Name = (String.Join(", ",
String.Join(",",
New String() {item.Last_Name, item.First_Name, item.Title}).Split(
New Char() {","}, System.StringSplitOptions.RemoveEmptyEntries)))
})
Dim query2 = (From items In query1
From demogAKA In data_Demogs.Where(Function(a) items.ID_Demog = a.ID_Demog_AKA).defaultifempty
From DType In tbl_Disease_Types.Where(Function(a) items.ID_Disease_Type = a.ID_Disease_Type).defaultifempty
From DGroup In tbl_Disease_Groups.Where(Function(a) items.ID_Disease_Group = a.ID_Disease_Group).defaultifempty
From RFC In tbl_Reason_For_Calls.Where(Function(a) items.ID_Reason_For_Call = a.ID_Reason_For_Call).defaultifempty
From Phys In PhysNames.Where(Function(a) items.ID_Physician = a.ID).defaultifempty
Select
items.ID_Demog,
items.Last_Name,
items.First_Name,
AKA_Name = demogAKA.Last_Name + ", " + demogAKA.First_Name,
items.DOB,
items.Gender,
items.ST_Complete,
items.LT_Complete,
items.LT_Due_Date,
DType.Disease_Type_Abr,
DGroup.Disease_Group_Name,
RFC.Reason_For_Call,
items.ID_Physician,
Phys.Phys_Name
).distinct
console.writeline(Query2)
When I try to join my working query into the final query, I get the following error:
Invalid cast from 'System.String' to 'VB$AnonymousDelegate_0`2[[System.Object, mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934...
'Query1 removed to save space
Dim query2 = (From items In query1
From demogAKA In data_Demogs.Where(Function(a) items.ID_Demog = a.ID_Demog_AKA).defaultifempty
From DType In tbl_Disease_Types.Where(Function(a) items.ID_Disease_Type = a.ID_Disease_Type).defaultifempty
From DGroup In tbl_Disease_Groups.Where(Function(a) items.ID_Disease_Group = a.ID_Disease_Group).defaultifempty
From RFC In tbl_Reason_For_Calls.Where(Function(a) items.ID_Reason_For_Call = a.ID_Reason_For_Call).defaultifempty
From Phys In tbl_Physicians
Where items.ID_Physician = Phys.ID_Physician
Group Join f In tbl_Titles On Phys.ID_Title Equals f.ID_Title
Into Matched = Group
From m In Matched.DefaultIfEmpty()
Select
items.ID_Demog,
items.Last_Name,
items.First_Name,
AKA_Name = demogAKA.Last_Name + ", " + demogAKA.First_Name,
items.DOB,
items.Gender,
items.ST_Complete,
items.LT_Complete,
items.LT_Due_Date,
DType.Disease_Type_Abr,
DGroup.Disease_Group_Name,
RFC.Reason_For_Call,
items.ID_Physician,
PhysName = Function(a) String.Join(", ",
String.Join(",",
New String() {Phys.Last_Name, Phys.First_Name, m.Title}).Split(
New Char() {","}, System.StringSplitOptions.RemoveEmptyEntries))
).distinct
console.writeline(Query2)
After a long time playing around in LINQpad, and then finally re-reading JM's answer to a former question I had, I realized what I was doing wrong.
As per his post:
The problem is that, while LINQ in general has no issue with that code, LINQ to Entities does. LINQ syntax is the same for every provider but the implementation under the hood differs and, in the case of LINQ to Entities, your LINQ code has to translated to SQL and, in this case, there's no mapping from String.Join to SQL. That code would work fine with LINQ to Objects so one solution is to push that operation out of the original query and into a LINQ to Objects query. That would mean selecting the raw data with your LINQ to Entities query, calling ToList or ToArray on the result to materialise the query, then performing another query on that result. That second query will be LINQ to Objects rather than LINQ to Entities and so String.Join will not be an issue.
So... Once I realized I needed to push out the String.Join, I ended up with the following code:
Dim DispList = (From items In MastList
From demogAKA In dbACL.data_Demog.Where(Function(a) items.ID_Demog = a.ID_Demog_AKA).DefaultIfEmpty
From DType In dbACL.tbl_Disease_Type.Where(Function(a) items.ID_Disease_Type = a.ID_Disease_Type).DefaultIfEmpty
From DGroup In dbACL.tbl_Disease_Group.Where(Function(a) items.ID_Disease_Group = a.ID_Disease_Group).DefaultIfEmpty
From RFC In dbACL.tbl_Reason_For_Call.Where(Function(a) items.ID_Reason_For_Call = a.ID_Reason_For_Call).DefaultIfEmpty
From e In dbACL.tbl_Physician.Where(Function(a) items.ID_Physician = a.ID_Physician).DefaultIfEmpty
Group Join f In dbACL.tbl_Title On e.ID_Title Equals f.ID_Title
Into Matched = Group
From m In Matched.DefaultIfEmpty()
Select
items.ID_Demog,
items.Last_Name,
items.First_Name,
AKALname = demogAKA.Last_Name,
AKAFname = demogAKA.First_Name,
items.DOB,
items.Gender,
items.ST_Complete,
items.LT_Complete,
items.LT_Due_Date,
DType.Disease_Type_Abr,
DGroup.Disease_Group_Name,
RFC.Reason_For_Call,
items.ID_Physician,
PLName = e.Last_Name,
PFname = e.First_Name,
PMI = e.Middle_Initial,
PTitle = m.Title
).Distinct.ToList().Select(Function(a) New With {
a.ID_Demog,
a.Last_Name,
a.First_Name,
.AKA_Name = (String.Join(", ",
String.Join(",",
New String() {a.AKALname, a.AKAFname}).Split(
New Char() {","}, System.StringSplitOptions.RemoveEmptyEntries))),
a.DOB,
a.Gender,
a.ST_Complete,
a.LT_Complete,
a.LT_Due_Date,
a.Disease_Type_Abr,
a.Disease_Group_Name,
a.Reason_For_Call,
a.ID_Physician,
.PName = (String.Join(", ",
String.Join(",",
New String() {a.PLName, a.PFname, a.PTitle}).Split(
New Char() {","}, System.StringSplitOptions.RemoveEmptyEntries)))
}).ToList()
Trying to pass column name as parameter but JPA sets it as a value surrounding it with single quotes.
#NamedNativeQueries({
#NamedNativeQuery(
name = "Genre.findAllLocalized",
query = "SELECT "
+ " CASE "
+ " WHEN ? IS NULL THEN genre_default"
+ " ELSE ? "
+ " END localized_genre "
+ "FROM genre ORDER BY localized_genre")
})
Then:
List<String> res = em.createNamedQuery("Genre.findAllLocalized")
.setParameter(1, colName)
.setParameter(2, colName)
.getResultList();
The problem is that the column names being passed are taken as values so the result will return result list with repeated values of "col_name" instead of selecting the value of the column passed as parameter.
Is this achievable?
Basically it makes no sense to create a prepared query like this, how would you name that query anyway: "*"? So the short answer is: no.
But you could create named queries dynamically if this matches your requirement:
String colName = "colName";
String query = "SELECT WHEN " + colName + " IS NULL THEN genre_default";
Query query = entitymanager.createQuery(query);
Probably using a criteria builder is more the way you want to use JPA (code from https://en.wikibooks.org/wiki/Java_Persistence/Criteria):
// Select the employees and the mailing addresses that have the same address.
CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
CriteriaQuery criteriaQuery = criteriaBuilder.createQuery();
Root employee = criteriaQuery.from(Employee.class);
Root address = criteriaQuery.from(MailingAddress.class);
criteriaQuery.multiselect(employee, address);
criteriaQuery.where( criteriaBuilder.equal(employee.get("address"), address.get("address"));
Query query = entityManager.createQuery(criteriaQuery);
List<Object[]> result = query.getResultList();
Just a quick question about LINQ, I want to use a value from the returned dataset to lookup a value and return this. The line I am struggling with is .ViewingNotes = New Viewing(pt.ProspectId).GetViewings().Columns(7).ToString(). Is this possible?
With BusinessLayerObjectManager.Context
Return (From p As [Property] In .PropertySet
Join pt As Prospect In .Prospects On pt.Property.propertyID Equals p.propertyID
Where (p.Development.DevelopmentID = devId)
Select New DevelopmentList With {
.Apartment = p.propertyApartment + " " + p.Development.Name,
.PropertyId = p.propertyID,
.Client = pt.Client.clientFirstname + " " + pt.Client.clientLastname,
.ClientId = pt.Client.ClientID,
.ProspectiveDate = pt.prospectiveDate,
.ProspectiveStatus = pt.prospectiveStatus,
.Agent = pt.Client.userID,
.ViewingNotes = New Viewing(pt.ProspectId).GetViewings().Columns(7).ToString(),
.PropertyStatus = ""
}).ToList()
End With
Thanks in advance.
I suspect not, when the compiler tries to convert the 'Viewing(pt.ProspectId).GetViewings().Columns(7).ToString()' bit to SQL it will get very confused. You would need to do it in 2 stages.
Do the first Linq-to-entity select first returning just pt.ProspectId, with the .ToList() intact. Then use the results to do some more linq, linq-to-linq if you like, where you can do the lookup using a lambda.
I have a question about Entity Framework. Please answer if you know answer on this. I have such query :
String queryRaw =
"SELECT " +
"p.ProductName AS ProductName " +
"FROM ProductEntities.Products AS p " +
"INNER JOIN CategoryEntities.Categories AS c " +
"ON p.CategoryID = c.CategoryID ";
ObjectQuery<DbDataRecord> query = new ObjectQuery<DbDataRecord>(queryRaw, entityContext);
GridView1.DataSource = query;
GridView1.DataBind();
Particularly I want to join few tables in one query, but I can NOT use LINQ and can NOT use ObjectQuery with objects mapped to DB fields inside my query. Because each entity creates dynamically. So this is what i can NOT use :
msdn.microsoft.com/en-us/library/bb425822.aspx#linqtosql_topic12
msdn.microsoft.com/en-us/library/bb896339%28v=VS.90%29.aspx
The question is can I use something like this instead of using objects?
query.Join ("INNER JOIN CategoryEntities.Category ON p.CategoryID = c.CategoryID ");
The purpose is to use Join method of ObjectQuery with syntax as in Where method :
msdn.microsoft.com/en-us/library/bb338811%28v=VS.90%29.aspx
Thanks, Artem
Any decision i see right now is to temporary convert ObjectQuery to string, add joined table as string and then convert it back to ObjectQuery :
RoutesEntities routesModel = new RoutesEntities(entityConnection);
String queryRaw = "SELECT " +
"rs.RouteID AS RouteID, " +
"rs.LocaleID AS LocaleID, " +
"rs.IsSystem AS IsSystem " +
"FROM RoutesEntities.Routes AS rs ";
_queryData = new ObjectQuery<DbDataRecord>(queryRaw, routesModel);
var queryJoin = _queryData.CommandText + " INNER JOIN LocalesEntities.Locales AS ls ON ls.LocaleID = rs.LocaleID ";
_queryData = new ObjectQuery<DbDataRecord>(queryJoin, routesModel);
Maybe someone has more consistent suggestions?
Finally I Found a better solution for this, we can use Sub Query inside main Query. For example :
var db = CustomEntity();
ObjectQuery<Categories> query1 = db.Categories.Where("it.CategoryName='Demo'").Select ("it.CategoryID");
var categorySQL = query1.ToTraceString().Replace("dbo", "CustomEntity"); // E-SQL need this syntax
ObjectQuery<Products> query2 = db.Categories.Where("it.CategoryID = (" + categorySQL + ")");
Some example is here :
http://msdn.microsoft.com/en-us/library/bb896238.aspx
Good luck!
I want to declare a variable to hold the query result from LINQ to SQL like to the following:
Dim query As IQueryable(Of Student)
If isNoUserName Then
query = From st In db.Students _
Order By st.AssignedId Ascending _
Where (st.studentId = studentId _
Select st
Else
'' error here
query = From st In db.Students _
Order By st.firstName Ascending _
Join user In db.MSUsers On user.UserId Equals st.UserId _
Where st.studentId = studentId _
Select st.firstName, st.lastName, user.userName
End If
Return query
Error : conversions from 'System.Linq.IQueryable(Of )' to 'System.Linq.IQueryable(Of Student)'.
How do I declare variable "query" to hold both data from "Student" and "User" tables?
Thank you.
query is declared as being IQueryable<Student>, but it you look at the second query, you aren't actually returning students - you are returning a compiler-generated type composed of firstName, lastName and userName. Try changing the second query to end with:
Select st;
Edit:
Re needing data other than st, then you might try a trick to give query a type; I'll use C# for my illustration, as my VB is read-only:
var query = Enumerable.Repeat(new {firstName="",lastName="",userName=""}, 0);
...
if(isNoUserName) {
query = ...
select new {st.firstName, st.lastName, userName = ""};
} else {
query = ...
select new {st.firstName, st.lastName, user.userName };
}