How to design a database for templated logging purposes?

In my web application I want to log certain user interactions etc, like "User ABC joined Group XYZ" Therefore I want to set up a logging mechanism that logs into a Mssql database. I'm now trying to find a good database design to achieve flexibility.

First of all, I don't want to log strings like "Use开发者_运维技巧r ABC joined Group XYZ". I'd like to separate the content "ABC" and "XYZ" from the template. So I'm looking for a templated logging database.

Something like this:

table: UserLog

IDLog int primary key
IDUserLogTemplate int foreign key
date datetime

table UserLogTemplate

IDUserLogTemplate int PK
TemplateString varchar (like 'User {0} joined Group {1}')
IDUserLogType int FK

table UserLogType

IDUserLogType int PK
Name varchar
Description varchar

table UserLogContent

IDUserLogContent int PK
IDLog int FK
PlaceholderPosition int (like '0')
Value varchar (like "ABC")

I think this database structure would give me enough flexibility to add/remove/edit specific log types (like 'User ABC did something else'). For example I might want to add some information to a specific log entry for future entries. Therefore I create a new UserLogTemplate that references the same UserLogType. That is how I would achieve downward compatibility.

Is that a database design that will work? Do you suggest a better design?

I'm not just trying to hock one of my applications, but I have developed an application logging tool that allows you to store custom meta-information along with individual log entries. It runs using CouchDB, a Document-oriented database, (non-relational, which is what SQL Server is) which make storing and retrieving loosely-structured information like this much easier.

If you are interested, check it out on GitHub and/or shoot me an email. I would love to help you get started with it, and perhaps it'd be a much better fit for this type of "not-so-structured" data.

I've decided to use the db design posted by myself.