Multiple foreign keys from one table linking to single primary key in second table

Posted by croker10 on Stack Overflow See other posts from Stack Overflow or by croker10
Published on 2010-12-30T21:43:39Z Indexed on 2011/01/10 13:53 UTC
Read the original article Hit count: 231

Filed under:

sql

|

foreign-keys

|

primary-key

|

joins

Hi all,

I have a database with three tables, a household table, an adults table and a users table. The Household table contains two foreign keys, iAdult1ID and iAdult2ID. The Users table has a iUserID primary key and the Adult table has a corresponding iUserID foreign key. One of the columns in the Users table is strUsername, an e-mail address.

I am trying to write a query that will allow me to search for an e-mail address for either adult that has a relation to the household. So I have two questions, assuming that all the values are not null, how can I do this?

And two, in reality, iAdult2ID can be null, is it still possible to write a query to do this?

Thanks for your help. Let me know if you need any more information.

© Stack Overflow or respective owner

Related posts about sql

SQL SERVER – Concat Strings in SQL Server using T-SQL – SQL in Sixty Seconds #035 – Video

as seen on SQL Authority - Search for 'SQL Authority'
Concatenating string is one of the most common tasks in SQL Server and every developer has to come across it. We have to concat the string when we have to see the display full name of the person by first name and last name. In this video we will see various methods to concatenate the strings. SQL… >>> More
SQL SERVER – Concat Function in SQL Server – SQL Concatenation

as seen on SQL Authority - Search for 'SQL Authority'
Earlier this week, I was delivering Advanced BI training on the subject of “SQL Server 2008 R2″. I had great time delivering the session. During the session, we talked about SQL Server 2010 Denali. Suddenly one of the attendees suggested his displeasure for the product. He said, even though… >>> More
Error with SQL Server Setup 2012 on Windows 2012

as seen on Server Fault - Search for 'Server Fault'
I am trying to install SQL Server on Windows 2012. I was able to finally get the wizard up and running after making some changes on the server, but now it fails no matter what I do with the following error: TITLE: SQL Server Setup failure. SQL Server Setup has encountered the following error: … >>> More
How can I detect which version of SQL (eg SQL 2008 or SQL Azure)

as seen on Stack Overflow - Search for 'Stack Overflow'
I need to detect which version of SQL I am dealing with to perorm various tasks, I need specifically detect if I am on SQL 2008 or SQL Azure. How can I do this with detection code written in SQL? >>> More
Nested SQL Select statement fails on SQL Server 2000, ok on SQL Server 2005

as seen on Stack Overflow - Search for 'Stack Overflow'
Here is the query: INSERT INTO @TempTable SELECT UserID, Name, Address1 = (SELECT TOP 1 [Address] FROM (SELECT TOP 1 [Address] FROM [UserAddress] ua INNER JOIN UserAddressOrder uo ON ua.UserID = uo.UserID WHERE ua.UserID = u.UserID ORDER BY uo.AddressOrder ASC) q ORDER BY AddressOrder… >>> More

Related posts about foreign-keys

Foreign keys in django admin list display

as seen on Stack Overflow - Search for 'Stack Overflow'
If a django model contains a foreign key field, and if that field is shown in list mode, then it shows up as text, instead of displaying a link to the foreign object. Is it possible to automatically display all foreign keys as links instead of flat text? (of course it is possible to do that on a… >>> More
Multiple foreign keys in one table to 1 other table in mysql

as seen on Stack Overflow - Search for 'Stack Overflow'
Hey guys, I got 2 tables in my database: user and call. User exists of 3 fields: id, name, number and call : id, 'source', 'destination', 'referred', date. I need to monitor calls in my app. The 3 ' ' fields above are actually userid numbers. now i'm wondering, can i make those 3 field foreign… >>> More
Create automatically table that is composed by its primery key and 2 other foreign keys

as seen on Stack Overflow - Search for 'Stack Overflow'
I have table A with a primary id, a table B with a primary key id also and another table C with a primary key id and rows Aid and Bid where Aid and Bid are foreign keys of C and the primary keys of A and B respectively. One way of populating these DB would be populating table A, table B and table… >>> More
Foreign keys with Rails' ActiveRecord::Migration?

as seen on Stack Overflow - Search for 'Stack Overflow'
Hello, I'm new to Ruby on Rails (I know Ruby just decently though) and looking at the Migration tools, it sounds really awesome. Database schemas can finally (easily) go in source control. Now my problem with it. When using Postgres as the database, it does not setup foreign keys. I would like the… >>> More
Working with foreigh keys - cannot insert

as seen on Stack Overflow - Search for 'Stack Overflow'
Hi everyone! Doing my first tryouts with foreign keys in a mySQL database and are trying to do a insert, that fails for this reason: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails Does this mean that foreign keys restrict INSERTS as well as… >>> More