SQL Server – How to Filter Values in Two Tables Using Inner Join

Ok, I am making a lot of assumptions (INT instead of VARCHAR(50) being one of them) with this answer, so feel free to correct me if needed. The problem with option B is that it introduces a new join to relate Users to Alerts without any real added benefit. If joining on the UserID, it is best to index the UserID, so you can utilize seeks for your joins.

For Option A, UserID will be the clustering key (index key for the clustered index) on the Users table. UserID will be a nonclustered index key on Alerts table. This will cost 16 bytes per Alert.

For Option B, UserID will be the clustering key on the Users table. UserId will probably be the clustering key in UserMap too, to make joining more efficient. UserKey (assuming this is an INT) would then be a nonclustered index key on the Alerts table. This will cost 4 bytes per Alert. And 20 bytes per UserMap.

Looking at the big picture, one relationship, for Option A, costs 16 bytes of storage, and involves 1 join operation. Whereas, one relationship, for Option B, costs 24 bytes of storage, and involves 2 join operations.

Furthermore, there are a possibility of 340,282,366,920,938,000,000,000,000,000,000,000,000 uniqueidentifiers and only 4,294,967,296 INTs. Implementing a uniqueidentifier to INT map for a this type of relationship could cause unexpected results when you start reusing INTs.

The only reason for creating this type map table, is if you plan on creating a Many to Many relationship between Users and Alerts.

Taking all of this into consideration, I would recommend Option A.

I hope this helps,

Matt

If I understand your requirements correctly....

I would just use the natural key, LanguageCode-CultureCode ("en-US," for example). It's small enough. (I'm using the entire "en-US" as the primary key to differentiate it from "en-GB," for example.)

CREATE TABLE [dbo].[Language](
    [Language] [char](2) NOT NULL,
    [Culture] [char](2) NOT NULL,
    [LanguageCode]  AS (([Language]+'-')+[Culture]) PERSISTED NOT NULL,
 CONSTRAINT [PK_Language] PRIMARY KEY CLUSTERED 
(
    [Language] ASC,
    [Culture] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY],
 CONSTRAINT [LanguageCode] UNIQUE NONCLUSTERED 
(
    [LanguageCode] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

CREATE TABLE [dbo].[Language_Text](
    [LanguageID] [varchar](5) NOT NULL,
    [LanguageCode] [varchar](5) NOT NULL,
    [LanguageName] [nvarchar](20) NULL,
 CONSTRAINT [PK_Language_Text] PRIMARY KEY CLUSTERED 
(
    [LanguageID] ASC,
    [LanguageCode] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]

GO

ALTER TABLE [dbo].[Language_Text]  WITH CHECK ADD  CONSTRAINT [FK_Language_Text_Language] FOREIGN KEY([LanguageCode])
REFERENCES [dbo].[Language] ([LanguageCode])
GO

ALTER TABLE [dbo].[Language_Text] CHECK CONSTRAINT [FK_Language_Text_Language]
GO

This should allow you to get all articles in en or sv, and you can also query for en-US or sv-SE. Presumably, although it wasn't in your example, you could also query for en-CA, fr-CA, en, fr, or CA.

Edit--I'm sorry, you're right, no search by Culture in my old code. Revamped above, sorry. Here's a sample of content:

Language:

Language-Culture-LanguageCode
en  US  en-US
sv  SE  sv-SE

Language_Text:

LanguageID-LanguageCode-LanguageName
en-US   en-US   English
en-US   sv-SE   Engelska
sv-SE   en-US   Swedish
sv-SE   sv-SE   Svenska

Searching by Culture (Canada):

SELECT        test.dbo.Language_Text.LanguageID, test.dbo.Language_Text.LanguageCode, test.dbo.Language_Text.LanguageName
FROM            test.dbo.Language_Text INNER JOIN
                         test.dbo.Language ON test.dbo.Language_Text.LanguageID = test.dbo.Language.LanguageCode
WHERE        (test.dbo.Language.Culture = 'CA')

Searching by Language (French):

SELECT        test.dbo.Language_Text.LanguageID, test.dbo.Language_Text.LanguageCode, test.dbo.Language_Text.LanguageName
FROM            test.dbo.Language_Text INNER JOIN
                         test.dbo.Language ON test.dbo.Language_Text.LanguageID = test.dbo.Language.LanguageCode
WHERE        (test.dbo.Language.Language = 'fr')

Searching by LanguageCode (Swedish):

SELECT LanguageName
  FROM [test].[dbo].[Language_Text]
  where (LanguageID = 'sv-SE')