ADO.NET :: How To Join 3 Related Tables With Linq To Sql
Nov 9, 2010
Here's my DB structure:
I have three tables.
User, Details, Optional
User has fields: ID, FirstName, LastName
Details has fields: ID, MyDetails1, MyDetails2, User_ID
Optional has fields: ID, MyOptions1, MyOptions2, User_ID
There is a 1 to many relationship with User & Detail (User ID & Detail User_ID)
There is a 1 to many relationship with User & Optional (User ID & Optional User_ID)
With that said, one user can have many details and/or many optionals
Now I'm trying to build a linq query that will say:
"where user id = x, select FirstName, LastName, all MyDetails1 from every record where User_ID == x, all MyOptions1 from every record where User_ID == x"
After the merge I should have one string that lists the distict user & all of their many fields:
I was trying to find out how I can join more than 2 tables using the LINQ-to-SQL syntax. For instance, joining 2 tables in SQL:
SELECT * FROM Table1 AS T1 INNER JOIN Table2 AS T2 ON T1.Key=T2.Column1WHERE T2.Key='17';
can be expressed as:
var Result = from T1 in DbContext.Table1 join T2 in DbContext.Table2 on T1.Key equals T2.ForeignKey where T2.Key=17 select new { T1, T2 };
But how would I join 3 or more tables using LINQ? For example:
SELECT * FROM (Table1 AS T1 INNER JOIN Table2 AS T2 ON T1.Key=T2.Column1) INNER JOIN Table3 AS T3 ON T3.Key=T2.Column2 WHERE T2.Key='37';
I've been searching and experimenting and I cannot seem to find any informraiton on this. One example I found involves putting the result for the frist join into a temp object, and then performing the second join. I'm not sure performance-wise if that's the same as doing a 3-table join directly using a single SQL statement.
The main problem is that I recieve the following message:
"base {System.SystemException} = {"Unable to create a constant value of type 'BokButik1.Models.Book-Author'. Only primitive types ('such as Int32, String, and Guid') are supported in this context."}"
based on this LinQ code:
[Code]....
How shall I solve this problem to get a class instance that contain with property title and Book-AuthorID?I also have tried making some dummy by using "allbooks" relation with Code Samples from the address
http://www.hookedonlinq.com/JoinOperator.ashx. Unfortunately, still same problem.
I also have taken account to Int32 due to entity framework http://msdn.microsoft.com/en-us/library/bb896317.aspx. Unfortunatley, still same problem.
Using database with 3 tables and one of them is a many to many relationship. This database is used in relation with entity framework
I'm working with asp.net 3.5 WebForms and LINQ to Entities.
I created the database with their relationships, but when I go to import the data with LinqToEntities, some reports and have not seen any reports 1 to 1.
I can create them after the reports have imported the tables LinqToEntities?
I have a question about Entity Framework. answer if you know answer on this. I have such query :
[Code]....
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 : [URL]
The question is can I use something like this instead of using objects?
[Code]....
The purpose is to use Join method of ObjectQuery with syntax as in Where method :[URL]
I have two tables namely "CategoryMapping" and "PartnerCategory"...The partnercategory table has foreign key with categorymapping on CategoryID...
let us say categorymapping should be filed first then partnercategory should be filed based on the categories defined in categorymapping. For example my two tables have the following data:
I want to get data from Projects(which have CourseId) and related CourseName from Courses table.
I have written following code:
var projects = from n in db.Projects join c in db.Courses on n.CourseId equals c.ID orderby n.Name select new { Project = n, Course = c }; return View(projects.ToList());
and I get error:
The model item passed into the dictionary is of type 'System.Collections.Generic.List1[<>f__AnonymousType22[ProjectManager.Models.Project,ProjectManager.Models.Course]]', but this dictionary requires a model item of type 'System.Collections.Generic.IEnumerable`1[ProjectManager.Models.Project]'.
What I need to do in Controller and in View to display this data?
I'm having trouble doing a left outer join with multiple generic lists tables. I've been researching for hours and there isn't a whole lot out there on this subject and VB (at least what I found).
I have the following Linq query:
Dim DataForGridview = (From s In S1 _ Join c In C1 On c.ID Equals s.ID _ Join v In V1 On v.ID Equals s.ID _ Select New With { _ .dataFieldID = s.ID, _ .dataField1 = s.dataField1, _ .dataField2 = c.dataField2, _ .dataField3 = c.dataField3, _ .dataField4 = c.dataField4, _ .dataField5 = v.dataField5 _ }).ToList()
S1 has a count of 30. V1 has a count of 20. C1 has a count of 10. This query joins the three but ends up with a count of only 10 based on the datakey ID and, of course, only shows those 10 in the gridview.
I would like to show all 30 from S1 in the gridview with blank fields wherever V1 and C1 do not have data. From what I've read I need to do a left outer join. However, all examples I've found are with two datasets.
I've tried multiple times expanding on what I've found by changing it to a group join and also adding the .DefaultIfEmpty() property in the query, but nothing is working.
How can I change the above query to a left outer join with these multiple tables?
I'm trying to build a linq2Entity/gridview function for a forum, that draws data from multible tables.The result should be: Get the latest 10 threads that user(xx) has replyed in, that is not disabled or has a subject that is not allowed.Include information on the last post, thread owner user, and last post user, in each thread. ere is my code... is returns the correct threads and some that should not be there.
if you have two table inner join like SELECT* From A INNER JOIN B on A.ID = B.IDSay A and B tables both have Username values but A's username is Test, and B's username is Test2When I do Eval("Username") it always print out "Test", how can I configure it to print out "Test2"... meaning how to specify which table's value to put using eval.. is there something like Eval(B.("Username"))??
I have a scenario, I will pass a StatusID , According to that StatusID , The rows will be fetched from a table[tblEventStatus] and newly fetched row has to fecth the data from another table [tblEvent].
TABLE 1 SELECT I.STUNA ,S.SNO ,SUM(B.AMT * Y.YEAR) AS AMT FROM STUDENT S LEFT JOIN INFO I ON S.SNO = I.SNO LEFT JOIN BONUS B ON S.SNO = B.SSNO LEFT JOIN YEAR Y ON S.SNO = Y.SSNO STUNA SNO AMT JOHN A 10 LISA B 20 ALLEN C 100
TABLE 2 SNO AMT A 1 B 2 C 3 D 5
I WANT TO HAVE RESULT LIKE THIS (TABLE1 + TABLE2)
STUNA SNO AMT JOHN A 11 LISA B 22 ALLEN C 103 EDDIE D 5
I TRIED USE THIS QEURY
SELECT I.STUNA ,S.SNO ,SUM(B.AMT) AS AMT FROM STUDENT S LEFT JOIN INFO I ON S.SNO = I.SNO LEFT JOIN BONUS B ON S.SNO = B.SSNO LEFT JOIN ( SELECT SNO, SUM(AMT) AS AMT FROM TABLE2 GROUP BY SNO ) T2 ON S.SNO = T2.SNO GROUP BY I.STUNA,S.SNO THE RESULT IS STUNA SNO AMT JOHN A 11 LISA B 22 ALLEN C 103
THE "EDDIE" WAS MISS. ALSO I TRY USE CROSS JOIN... THE RESULT IS STILL NOT CORRECT.
i need to join two tables in different databases, how it can be done??? and if i want to use sqldatasource control to bind results to some data-bound control how can I configure my sqldatasource control???
I am new to MVC and am trying to join 2 SQL tables together and return them in a Json. One table is OutreachProgram. The other table is UserInfo. I want to return the rows from the OutreachProgram table that match on CenterID with the UserInfo table.
The code that exists now will pull all rows from the OutreachProgram table. I can't figure out how to add the UserInfo table to the query to make it work.
JsonGrid <OutreachProgram> grid = new JsonGrid<OutreachProgram>(db.OutreachProgram, new OutreachProgramFilter()); public Array GetItems(IQueryable<OutreachProgram> source) { return (from r in source.AsEnumerable() select new { ID = r.OutreachProgramID, CenterID = r.CenterID, DateOutreachProvided = r.DateOutreachProvided.ToShortDateString(), NameOfProvider = r.NameofProvider.ToString(), }).ToArray(); }
t1 : id FirstName Age 1 Joe 22 2 James 33 3 Bart 28 t2: id LastName 1 Coymer 2 Manes
I can combine the data from the two tables using an inner join.
1 Joe 22 CoyLap 2 James 33 Manes
The problem though is that the person "Bart" with an Id of 3 is left out because he does not have an entry in the second table.So how can I include Bart in the output in such a way that the output might look like this:
1 Joe 22 CoyLap 2 James 33 Manes 3 Bart null null
Or spaces can instead appear for Barts last name and age instead of null.Basically I just need Bart in the output as well even though he has no age and last name.
I need to join some tables to get the matching records. I often have to ask around to see how certain tables could be joined. Is there any way to query the information schema or some thing else to see what columns/values match in certain tables in order to figure out how tables should be joined.
I have a select query which is executing well. Now, I want to add one more field to that query. That field is not in the current query table, It is in the another table.
How do I join those two tables and get that field value in the existing select query.?
Basically I want to JOIN a table from a MySQL database to a table from a MSSQL database. The reason is because I don't own the MySQL database and I only have SELECT privileges to it. For my ASP.NET application, I need to create two new tables. I have my own MSSQL DB and I have an SA account for it. Is this possible? This is how I connect to MySQL:
[Code]....
I think the problem here is that I need 2 open database connections for the DataAdapter to use?
I have two SQL Server tables with Primary Keys (PK) and a Foreign Key (FK) linking the two tables:
1) Table "Order"
OrderID, int, PK AddressID, int, FK ...
2) Table "Address"
AddressID, int, PK City, nvarchar(50) ...
Then I've created an (ADO.NET) Entity Data Model out of those two tables. Now on my (ASP.NET) webpage I put a GridView with an EntityDataSource. In my GridView I want to display two columns:
OrderID City (belonging to that order and linked by the AddressID-key) How can I do that? My problem is: When I configure the Entity Data Source I can select an "EntitySetName" which can be either "Order" or "Address" but not both, nor can I select any kind of relationship. If I select "Order" as EntitySetName then in the GridView I can add the columns
OrderID Address Address.AddressID
Adding the column "Address" displays empty cells. Adding "OrderID" and "Address.AddressID" displays the expected IDs. But how can I add the "City" of the related address to my GridView? Edit: Clarification:
The Entity Framework has created a class "Order" and a class "Address" corresponding to the database tables. The class "Order" has a reference to an "Address" object as a navigation property, corresponding to the 1-n relationship between Address and Order table. Basically I want to have a column in my GridView which displays Order.Address.City. I have tried to add a bound field with "Address.City" as data field to the GridView but it results in a runtime error ("no such property...").
I would like to update new records that get inserted in DataSet to Sql Server Database. Below is a working example of how to do this if you use "DataAdapter.Fill(ds)".
But i don't want to fill data, becouse i don't need data, i only need shema (I will use this dataset to insert new data to Sql), so i would like to use "DataAdapter.FillSchema(ds)"
