SaaS- Tenant Specific Lookup Data in Shared Database

Question

I am developing multitenant SaaS based application and going with Shared Database for storing all the tenant records with help of TenantId column.

Now the problem is i h

Answer 1

We have a saas based database and we keep common data and tenant data in the same table.

Concept

GamesTable

    Id NOT NULL
    TenantId NULL
    GameName NOT NULL
    Add a unique key for TenantId and GameName

• if TenantId is NULL you know it is common data
• if TenantId is NOT NULL you know it belongs to a specific tenant and who exactly.

"Is there any other DB design which allows me to do mix both common master data and tenant master data with JOIN?"

Yes

SELECT *
  FROM GamesTable where TenantId = 'your tenant id'
  UNION
SELECT *
  FROM GamesTable where TenantId IS NULL  -- common 

Answer 2

You can merge the tables leaving TenantId as NULL for records you wish to not be Tenant specific.

Games

Id
TenantId
GameName

The you can query that table in a Join with:

...
FROM
    Games
    INNER JOIN UserGames ON
        UserGames.GameId = Games.Id

WHERE
    Games.TenantId = @tenantId OR
    Games.TenantId IS NULL

This will save you the trouble of ensuring that the Id is unique between the tables, unless you are using a UNIQUEIDENTIFIER for the Id.

Answer 3

This is the design I would then use.

Games

Id
GameName
IsTenantSpecific
SomeGameSpecificColumn

TenantGames

GameId
TenantId
SomeTenantSpecificColumn
AnotherTenantSpecificColumn

Then you can query that table in a Join with:

...
FROM
    Games
    INNER JOIN UserGames ON
        UserGames.GameId = Games.Id
    LEFT JOIN TenantGames ON
        TenantGames.GameId = Games.Id
WHERE
    TenantGames.TenantId = @tenantId OR
    (
        TenantGames.TenantId IS NULL AND
        IsTenantSpecific = 0
    )

Game specific fields can be put in the Games table. Tenant specific fields can be added to the TenantGames table, and those fields will be NULL if it is not a tenant specific customization.

Answer 4

This is a classic example of "many to many".

Table: Games
------------
GameID
GameName
IsMasterGame


TennantGames
------------------
GameID
TennantID

Tennants
------------
TennantID
...

To get the games for a given tennant, you would run a query like:

select *
from   Games
where isMasterGame = true
union
select * 
from Games g, 
TennantGames tg
where g.GameID = tg.GameID
and   isMasterGame = false
and   tg.TennantID = $currentTennant

(Apologies for archaic join syntax)

The union allows you to ask two questions: which games apply to everyone (isMasterGame = true), and secondly which games apply to the current tennant (tg.TennantID = $currentTennant). Logically, tennant games cannot also be master games.