DataSource Controls :: Sql Table Relationships / To Create A Dependency Between The 2 Tables
May 3, 2010
I have a table that contains item data. If the item is a particular type further information exists to describe the item. The additional information isn't that heavy however the number of records in relation to the main file will be quite small (less than
5%).
So I have 2 scenarios:1) Put the additional data in the main table and take tha hit on storage
2) Create an additional table and link the 2 together
If we were talking huge amounts of data I can understand that 2) would be the obvious choice but given the simplicity should 1) be a consideration?
If 2) is the answer - is it possible to create a dependency between the 2 tables when the item is 'that' particular type. In other words wnsure the addition data is populated for the required items and not others.
Does anyone no of any good resources regarding many-to-many relationships? More specifically on displaying data from many-to-many tables in ASP. Struggling to find anything but I may just be over complicating things!
So I am working on an MVC project to put to work the studying I have been doing. I am wrestling with the concept of Database Table relationships and foreign keys. I am working on a simple ecommerce site (displays products, shopping cart, user accounts..etc).
I have the following tables to start out with:
1) Products
2) Categories
I setup the Products and Categories tables to have a ProductId and CategoryId respectively. In my MySQL db, I created a FK on the Products Table to relate to the CategoryId field on the Categories table (I am not sure this was correct to begin).
My expectations for the way the database would handle the table relationship: I didn't want the DB to do anything with the products table if I deleted a category out of the Categories table, or vise versa. The only thing would be that the category field in a Product would be blank (or default) if their category was removed.
Finally, do I have to do anything in my entity classes such as in the Products class, add the ProductId to the Category.ProductId?
Eventually, when I Orders and Users to the project, I can see a relationship where each user -> many orders -> each order has many products -> and each product is in one category.
But I am having a hard time understanding how or if I should be setting up a Foreign key relationship in the two current tables of Products and Categories and if so how to setup my entity class in relation to that FK.
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.
i have a form view that takes fields from two tables 'Contract' and 'volunteers', however because i used a query builder,i have to input an insert statement. How do i create an insert statement for two tables in one query?
My dataset table data is from multiple tables (showing on a gridview),How to update the database tables using batch udpate on clicking submit, if the data is from a signle table, no problem, but I am not sure how to handle if the datais from mulitiple tables? If I have related tables, do I need put them in differet tables in the dataset?
I have a insert into statement thats inserting my numbers from a numeric text box on my aspx page. I am choosing the Amount Type then putting in a a number.
So i have a drop down that i select example Direct Charge then i enter 600.00 and click add it puts that in to the databse for me woot..
I then put in say Misc Credit and enter 200.00 it inserts in that into the database woot.
The look up table that has my amount types has a field called numeric opperator which is either + or - the Credit being a - and the Charge being a + then my stored procedure takes all my + numbers and adds them up and subtracts all the - numbers.
I want to change that so that it actuall be inserted into the table as a - number form the start. So I want choose Misc Credit enter 200.00 and click add then my event says o yea thats a credit insert 200.00 as -200.00
I would like to Select all entries in the GalleryAlbums table, but Order them (DESC) by date values in a column (upload_date) on the GalleryPhotos table. Both tables have a column "album_id"
A little confused how I might write this statement.
I'm assuming I need to use a pivot table from what I've found so far. However, every one that I've seen has not had the date setup like I have.
I have a Gridview on my page which I need to be populated like so
Date NCMR
1/1/10-1/31/10 #
2/1/10-2/28/10 #
I want to do this for 10 months... bottom record being the current month (or last month). I would also like the Date to format to January 2010 I used the above date format because that is how it is in the table. Basically, I need to know how to create the pivot table to search the table for 1/*/10, 2/*/10, etc
I am just getting started with entity framework with asp.net 3.5 using VS 2008
There are two tables, Categories & Subcategories:
Category table: CID, CategoryName Sub Category table: SID, CID, SubCategoryName I would like to get SID, CID, CategoryName, SubCategoryName in the gridview. Just as we write a select statement i.eSelect a.sid, b.cid, b.categoryname, b.subcategoryname from subcategories a inner join categories b on a.cid=b.cid & put the same in a gridview.
I was trying for the whole day & couldnt get atleast one url that would teach how to do it.
I have ASP.NET enviroment (C#) with SQL 2008 backend. I am using the ASP.NET membership provider. I need to create a table that contains member name, member role and third coumn (called "Registered for Conference"). I am using a button to initiate the action to call a stored procedure to write the selected value in the "Registered for Conference" column for the respective member.I know how to write the stored procedure, how to determine which user has processed their selection and how to write it to the "Registered for Conference" column of the table.I know that I can pull member name and member role with the following statement.
SELECT dbo.aspnet_Users.UserName, dbo.aspnet_Roles.RoleName FROM dbo.aspnet_Roles INNER JOIN dbo.aspnet_UsersInRoles ON dbo.aspnet_Roles.RoleId = dbo.aspnet_UsersInRoles.RoleId INNER JOIN dbo.aspnet_Users ON dbo.aspnet_UsersInRoles.UserId = dbo.aspnet_Users.UserId
I need to understand how to create the table that will contain the member name, member role and third coumn (called "Registered for Conference"). This table cannot be a static table. In other words, this table needs to refect any updates to roles or members
I am working on a multi-lingual application Assume the following:
Database has 50 tables and application has to support 5 languages
Which is the best way to design the database:
1. Include a langugae column for each table. Repeat the values for each language. Say i have a country table which has 100 countries in it. Then my design will contain 500 rows (100 for each langugae)
2. Create a separate table which will contain the translations for all the 50 tables in with a foreign key to the parent table.
I single table in SQL Server having 50 columns col_1 to col_50 having type varchar(MAX)..The table is having nearly 2 crore data into it which is unstructured i.e. just put in by bulk copy. I have to perform search operation on this table. How to index the table so as to make the search fast? or any other way to make the search fast.
I have a strange issue. I have a XSD file where I have created some TableAdapters. When I have reopened the XSD file it seems like I am not able to create a new table adapter since all the options which will come when I right click on the XSD file are disabled. I have cross verified whether I am on debugging mode but...I was not..(I am not even able to drag and drop an adapter from the left toolbox menu either)I am getting the same issue when I open the same XSD file on somebody else machine but I am able to create TableAdaperts in other XSDs.Can somebody suggest me a solution for this
how to create C# classes to represent one to many relationships in C#. I have a Customer and an Address table in my database. I also have a Customer class in my C# solution but how do I introduce the multiple address element? Do I have a separate Address class? Do I create a subclass in the Customer class or create a method in Customer called GetAddresses of type List which contains all of the relevant logic? In my code I need to be able to return a customer with all associated addresses and I just cannot picture the best way to achieve this using OOP.
