I have 2 questions.
I am developing a ASP.NET web application that uses the standard ASP.NET membership. We intend to have the membership tables in 1 database. We have 2 other databases that stores data for 2 different applications.
Shared - Membership info
DB1 - Application1
DB2 - Application2
Both applications uses the membership info in the "Shared" database.
The Shared database has a table called userdetals that will store additional users' info such as name, phone and job title for example.
However, DB1 also has a table called employees that store the same fields as name, phone and job title. Each employee may be an user.
Also for each table in DB1 and DB2, we keep audit trial, i.e. which user updated the tables in the database. Hence, we need to store UserID in the tables of DB1 and DB2.
We thought of having a Users table added in DB1 and DB2. So everytime a new user is created in Shared, the same user will be created in Users table in DB1 and DB2.
Our questions are:
What is the best way to maintain database integrity given the above setup? E.g. Each employee is assigned as an user. If any fields in DB1 such as username, name and phone is updated, then the same fields in Shared DB should be updated and vice versa.
Is it advisable to have membership database in a different database in our case? What is the best solution since almost all the tables in DB1 and DB2 references userID in the Shared database.
1.
The technology you are looking for is Merge Replication (http://bit.ly/KUtkPl). Essentially, you would create a common Users table on both databases, create a Merge Replication publisher on one application database, and then create a Merge Replication subscriber on the other application database. You could also set this up to synchronize the schema as well (which also means you only need to create the table once on the publishing database: it will push the table, schema with data, to the subscriber).
But if you are looking for more of a manual approach, I would not denormalize the user data to the employee(s) table, instead create a supplemental table and a view on each Application server. Kind of like inheritance in OOP: Any common data between the Employee table and Users table, leave on the shared user table. Any unique columns for the Employee, add to the supplemental table only and store on each database. The view would merge both the supplemental table and shared table. (http://bit.ly/9KPxt0)
Even if you do use Replication Services, I would still use this view design with the synchronized table.
You COULD update through the view, but I would not recommend that. It has been done before successfully in production, but there are too many constraints that could blow up (http://bit.ly/LJCJev). Instead update the table directly that holds the data.
Absolutely avoid "triggers that synchronize". Too risky (can cause an infant loop on your SQL server) and too much maintenance overhead.
2.
I would do the Merge Replication, it is just less for you to worry about and maintain after it is configured correctly. But your approach is OK if want something more manual or if you are not familiar with Replication services in SQL... just use the view noted above and you'll be set.
Easy way:
You can create link server to these databases.
And then create synonym to easy access to tables of each database.
Create trigger to update data when any data was updated on each table.
Related
In Oracle EBS, when we are doing data conversions and interfaces, loading data into Oracle from another system, how do we make sure the record is being locked? How do we make sure no other person is updating our records?
Oracle EBS seeded API's will take care about locking. We don't insert data into EBS base tables directly,
validate the data and insert into interface tables later we run oracle standard programs to import interface tables data into base tables.
These oracle standard programs use oracle seeded API to insert data into multiple base tables.
How do we make sure no other person is updating our records?
Developers use their own custom staging tables to import data into EBS.
when data upload staging tables to interface table maintain each interface data source is different, usually other persons don't update other interfaces records, We can't track if anyone updated from database backend tools like sql developer or TOAD. we can track transaction from last updated by column if they update from applications
If you have any specific issue related locking let us know
I want to create a new project on contract management system. In this I have to manage multiple organizations and want to create new instance in sql server dynamically for each organization in a saas environment. How is this posiible? I am using asp.net for development. Any help would be appreciated.
A true SaaS application has a single application and database. It has the ability to have multiple tenants use the application. All data in the database needs to know what tenant it belongs too.
For instance if you have a booking system: Your customers sign up to use the software and become a row in the customer table with an ID. When a booking is made it has a customerID column as a foreign key to the customer table. Then all reports, booking views etc are done for that tenant using their customer id. You as a service provider can then run reports on all customers/tenants for your own purposes. Multiple tenants can use the system and all their data be in the same set of tables. This then means when you need to cluster replicate backup etc it is a single db, and a single migration for schema updates.
See these wiki's on multitenancy and SaaS
This of course requires your DB schema (and your app) to support this - if you are unable to change the schema then there are a number of options to up a new DB based upon the technology you are using. If you are using code first EF, then there will be db creation and migration scripts you can use. Otherwise it may justhave to be a sql script you have to generate and then maintain and run this each time a new customer is required. Personally i would rather have a single DB with an appropriate schema.
I am building an asp.net apartment rental website. Currently, I do not utilize any membership functionality so there is no need to create long-term users, manage profiles or any extensive user related data.
I, however, have a separate database that contain tables for (Units, Locations, Tags..etc) with a simple User table that contain the following three field: name, email and phone#. Note that when the offer of the unit has expired then the created user will be deleted form the database.
Putting scalability and best practice in prospective, should I create ALL the tables in one giant database (ex: in the ASPNETDB if I want to use the default asp.net membership provider) or should I keep the membership database separate from the apartment-related database?
No reason not to have it all in a single database - less maintenance over the long term.
When using aspnet_regsql to create the base tables for forms authentication, is it recommended that these tables be stored inside of the application database catalog or should a database catalog just for authentication be created.
Thanks!
To clarify what jro said you can join across dbs but you'll lose some performance there.
Secondly if you want to maintain referential constraints you'll need the tables in the same DB. What I mean is if you have a new table for your app, say CustomerOrders, and you want to ensure the UserID column values exist in the Users table you'll need those in the same DB.
It doesn't matter.
If you need to eventually join records on the membership tables with your own catalog, I would suggest using an application database.
Otherwise, use your preferences for database management.
We are going to be selling a service that will be hosted by us, and each client we host will have their own database, but there will be one centralized website. I currently have a blank database with the few things that a new client will need. What is the best way to copy this database so I can setup another client? I want to be able to do this from an .aspx page. Thanks in advance!
Update:
By .aspx page, I just meant that I need to be able to kick off the process from an .aspx page.
Update2:
We're running SQL Server 2008.
Update 3: Referencing Cade Roux's answer... Thanks for a great answer, but...
What is the reason for merging all of the databases into one, and then distinguishing clients based on an identifier in each table? Wouldn't this greatly complicate the architecture of the entire product? I would need to add these Client ID columns to practically every table, and the DAL would need to know which client data its looking for. With the current setup I have, I just switch out the connection string in the DAL, depending on which user is accessing the site. That way, after the connection string is set, I never need to worry about finding client specific data! How do these approaches compare (and should I add this as a separate question?
You have a few different options:
You can detach your empty database, then when a user signs up, copy that database and mount it under a unique name for them and map it to their account in your master database, say.
You can create a database from scratch using scripts and populate any base data either from an online template database or scripting the base data and map it to their account in your master database.
You should seriously consider going to a multi-tenant architecture where all users are in the same database (with most tables having CustomerID columns to segregate the data) if you are going to have more than a few dozen customers.
Regarding your notes about option 3 - it depends on your application. Multi-tenant can be difficult to retrofit. On the other hand, managing and upgrading hundreds of individual customer databases can be difficult in the long haul.
There are previous Stack Overflow questions regarding this:
What are the advantages of using a single database for EACH client?
One database or many?
I think I'll see about re-tagging them with multi-tenant-db or something. Anyhow, I think that this comes up as a consideration secondary to your answer about a particular tactic does show the importance of including details about your overall goals in strategy in every question on StackOverflow.
Depending on what database you're using, there are several approaches. The simplest is to ask your database software to generate SQL code for creating the database and include that with your software. Another would be to just script out in C#/VB the steps needed to recreate your empty database.
Why the need for .aspx page?
You don't say what db version you're using but in SQL2005-2008, you have the ability to "script database as" and then "create to" and have it port the sql to a query window. You could then work with that to create a stored procedure that can be called from your .aspx page.
SQL Server has a system database called 'model'. Any database objects (tables, views, stored procedures) that exist in the model are added to any new database created.
You could create your 'client database' schema as model, and any new database would have all the same tables...
But, if you need to change your database schema later, your best option is to write change scripts which are part of your code-behind file. Since changes to the 'model' database are not propagated to existing databases, the application needs to detect and upgrade the database schema as necessary.
Disadvantage to this approach: If you want a database which isn't a 'client database' then you would need to create the database, and then delete the 'client database' tables.