ADO.NET :: Linq Examples With Multiple Tables - Using PK And FK In A Dataset?
Aug 19, 2010
Does anyone have some really great tutorials on how to use link with datasets that contain multiple tables that utilise primary key and foreign key relations? For eample
Table1
- id (PK)
- language
Table2
-id (PK)
-programmingword
Table3
-id (PK)
-languages_ID (FK)
-pgrammingword_ID (FK)
-translatedword
Linq search for: Table3.translatedword where Table1.Language ='french' and Table2.programmingword = "yes" does this make sense? im looking for exampes/ tutorials for how to do this? or can anyone recommend any good books on linq?
I was in need of exporting multiple tables in a DataSet to an Excel file with multiple sheets. I found a very good article in [URL].[URL] was able to successfully export each of my datatables in the dataset to excel worksheets. This solution worked for small number of rows. But when the data got larger I am consistently getting the system.outofmemoryexception. THis is because the code is using up the memory when creating excel.
I have 5 tables of which one has a primary key called "pid" as follows in patientdetails table the pid of a patient is used to compare the pid in remaining tables so the data in matching pid records can be stored in dataset. I tried using stored procedure to get them together in one dataset but it just doesent happen. This is my stored procedure,
[Code]....
I think the execution doesent proceed after the first if exists statements, because only the data in patientdetails is stored in dataset. and one more thing. all test tables need not contain a data against every pid in patientdetails table.
In my project, i have a DBML file which is acting as a Data Access Layer. There one more utility method that is converting the existing result into dataset. Below is my method:
I m having one dataset underwhich i have two DataTables ie Contact & Sales Order.In this two table my ContactId field is primary key in both the tables. I cot some code similar to the following code. But when i copy this code two my .net application it me an error saying semicolun expected ,etc as shown bellow.
Error 37 Invalid expression term 'in'
Because of this i m not able to test the code. can any body tell me how can i achive it . I kust want to inner join this two tables & want to store the result in another data table.
I have a dataset with 3 tables that are inner joined. Thsi dataset is connected to an object datasource which is connected to a gridview. So at runtime it displays data from the database. The problem is when I click on a save button to add information to the database it throughs me an error saying Failed to enable constraints. One or more rows contain values violating non-null, unique, or foreign-key constraints. But if i have two tables in my dataset it works 100%. But the problem i need that 3 tables in order to pull the required information. And if i populate the gridview using code to select the information from the database and insert information it also works 100%.
Here's the scenario: Buyers and Sellers (where all of the sellers have a unique D&B number).
I'm catering to the buyers, and I want them to be able to import a list of sellers based on the D&B number.
Here are the tables:
BuyersSellers - unique list of sellers - one record, no matter how many buyers work with them.BuyerSellers - lookup table - buyer_id, seller_id sets which buyers work with which sellers ImportedSellers - temp table that holds sellers the buyer wants to add.AllSellers - master table that has all known sellers with D&B numbers (remote database).
Here's the process:
Buyer uploads list of new sellers, they get added to ImportSellers tableMatch ImportedSellers against AllSellers (valid), ignore unmatched (invalid).Add valid ImportedSellers to the Sellers table if they don't exist.Create BuyerSeller records for all valid ImportedSellers - using data from AllSellers.Delete all valid ImportedSellers, leave the unmatched behind so they know what they need to fix.
I've got the upload and import working, but now I'm a little stuck on how to do all of the matching and inserting, and do it as quickly as possible.
I have a dataset that comprises of multiple tables (about 20) linked together with constraints to reflect the relational database. My question(s):
1) Will having multiple tables affect performance? I'm asking this as there are often times I would not need to get data for all the tables, but only for specific tables.
2) If it does affect performance, would breaking up the tables into their own datasets be the best solution. It seems to me that by doing that, you would lose the ability to apply constraints among tables and tables that might exist in multiple datasets will be subjected to replication.
I would like to have everything in one dataset as I get a view of the related tables and their relationships and also because the Fill method allow me to fill tables, maintaining the hierarchy of the data, but performance is still a key factor.
i m trying to bind my both grid with two tables which are in dataset i m trying but when i m binding my gridview it's always binding the second table see code
[Code]....
i already tried to bind both the gv1 and gv2 they both are displaying same table i.e department
I have a report which is runnin fine as it is using singe table Dataset(.xsd) . I want to expand the report and use more tables in it to show more information .
How can I do so. I am attaching my present code with this.
Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load Dim stdate, enddate As Date Dim sql As String start_date.Text = Session("startdate") end_date.Text = Session("endate") Dim dt As DateTime = DateTime.Parse(start_date.Text, System.Globalization.CultureInfo.GetCultureInfo("en-gb"))
I have a partitioned db where several tables have the exact same structure. I'm able to query the tables using linq, but only by quering the individual tables 1 at a time and by using the explicit table name. For example at the moment, I have 8 tables so I have something similar to the following:
[Code]....
Is there any way, that based on a certain value (stringValue), I could determine which table to query and then code the linq query just once?
I have a couple tables that are kind of unrelated - id like to search through both of them and create a type that i can sift through later
something like this doesnt work
[Code]....
I basically want to create a list of "AnimalSearchResults" that contains all dogs and all cats that have that name Whats the best way to do something like this?
I'm a newbie to this so bear with me. From what I've read online LINQ to Entity should see the relationships without having to specify the joins between multiple tables. I have a relationship that goes across 4 tables Employee, EmployeeDepartmentLink, EmployeeProjectLink, and Project. The idea is an employee can be in multiple departments and work on multiple projects with it being specified which department the employee is in for that project.
This is a C# MVC3 program connecting to a SQL database using VS 2010 Express.
I have no problem with running this query to find employees on a project:
[Code]....
Tring to do the reverse, finding projects that an employee worked on results in an error:
[Code]....
Error message: The specified type member 'EmployeeDepartmentLinks' is not supported in LINQ to Entities. Only initializers, entity members, and entity navigation properties are supported. So I have 2 questions,
1) Why would it work in one direction and not the other? I've played around with it for a couple days with the same results.
2) Does it matter that my primary key and foreign keys are not named the same since all the relationships are connected in SQL? Ex: in Employee (EmployeePK)--(EmployeeFK) in EmployeeDepartmentLink Trying different stuff in LINQPad I was able to get the 2nd query to work if I specified all the joins which I thought was not neccesary with LINQ to Entity. I converted an SQL query that I made on the server into a LINQ query below which works.
Is it possible to create a table class that can be used for multiple tables? For example, if I have some class:
[Code]....
In LINQ to SQL, this maps to a table with a name based on the class name, DBClass. However, suppose I want to use that class for multiple tables, and it could be an arbitrary number of tables. Is this possible
how can I display a linq query in a gridview that has data from multiple tables AND allow the user to edit some of the fields or delete the data from a single table?
I'd like to do this with either a linqdatasource or a linq query. I'm aware I can set the e.Result to the query on the selecting event. I've also been able to build a custom databound control for displaying the linq relations (parent.child).
However, I'm not sure how I can make this work with delete? I'm thinking I may need to handle the delete event with custom code.
I have two tables with a foreign key constraint how can I delete rows from both of them in one transaction? linq to SQL seems to call my deletes in the wrong order. Is there somewhere I can check and make sure the constraint is recognized properly by linq to SQL??
I'm looking for ideas on deleting data from the multiple SQL tables with LINQ (C#).
My existing solution does the following:
1. DeleteAllOnSubmit( Subset of the data from the child table)
2. DeleteAllOnSubmit( Subset of the data from another child table)
3. DeleteAllOnSubmit( Data from the parent table)
4. CommitChanges()
All this resides within a single method, which makes it ugly and not re-usable.
I have considered the following alternatives, but I decided not to use them:
1. Cascade delete on the tables.
2. Do a join on all tables from which I will remove the data, but I'm not sure yet whether I could pass a join query to DeleteAllOnSubmit().
3. Write stored procedure(s) to delete data from each table. I don't have the time to implement this due to a large number of tables and the time constraints.
I am getting Resultset from SQL server2005.It contains 4 tables.
Dataset ds=new Dataset();
ds=BLogiclayer1.TestMethod1(a,b,c,d);. This normal Dataset ds contains Resultset. ( I am working with RDLC reports. I added a Typed dataset to my project. I am using Typed Dataset as report dataset.) I want to add normal Dataset all the table values to Typed Dataset table as rows i. e. only one table in Typed dataset.I am trying like below.
//Typed Dataset name that I have added is salesdata.
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 have a stored procedure that returns 3 tables within the single recordset it returns. If I set a SqlDataSource to get data from this procedure, it works, but it only returns the first table. I want to have a GridView display the data from the 2nd or 3rd table using a SqlDataSource, but I can't figure out how to specify a particular table.
While there are some posts discussing this out there, I can't get a definitive answer about whether or not this is even possible (?). In a worst-case scenario, I can create another SP that only returns the 3rd table - but that creates a little maintenance headache that I would prefer to avoid.
I went through the demo video and was able to create what little it showed but now I am wanting to extend it. I want to add an Admin section with a login page.
Can someone show me source code from an site that uses more than HomeController and multiple db tables calling stored procedures and such?
