I will do my best to lay this out in text. Essentially, we have an application that tracks actions performed by users. Each action has it’s own table since each action has different parameters that need to be stored. This allows us to store those extra attributes and run analytics on the actions across multiple or single users rather easily. The actions are not really associated with each other other than by what user performed these actions.
Example:
- ActionTableA Id | UserId | AttributeA | AttributeB
- ActionTableB Id | UserId | AttributeC | AttributeD | AttributeE
- ActionTableC Id | UserId | AttributeF
Next, we need to allocate a value to each action performed by the user and keep a running total of those values.
Example:
ValueTable: Id | UserId | Value | ActionType | ActionId
What would be the best way to link the value in the value table to the actual action performed? We know the action type (A, B, C) – but from a SQL design perspective, I cannot see a good way to have an indexed relationship between the Values of the actions in the ActionsTable and the actual actions themselves. The only thing that makes sense would be to modify the ValueTable to the following:
ValueTable
Id | UserId | Value | ActionType | ActionAId(FK Nullable) | ActionBId(FK Nullable) | ActionCId(FK Nullable)
But the problem I have with this that only one of the 3 actionTableId columns would have a value, the rest would be Null. Additionally, as action types are added, the columns in the value table would too. Lastly, to programatically find the data, I would either a) have to check the ActionType to get the appropriate column for the Id or b) scan the row and pick the non-null actionId.
Is there a better way/design or is this just ‘the way it is’ for this particular issue.
EDIT
Attached is a diagram of the above setup:
Sorry for the clarity issues, typing SQL questions is always challenging. So I think your comment gave me an idea of something… I could have an SystemActionId table that essentially has an auto-generated value
SystemActions: Id | Type
Then, each ActionTable would have an additional FK to the SystemAction table. Lastly, in the ValueTable – associate it to the SystemActions table as well. This would allow us to tie values to specific actions. I would need to join the action tables to the system actions table where
JOIN (((SystemActions.Id = ActionTableA.Id) JOIN (SystemActions.Id = ActionTableB.Id)) JOIN (SystemActions.Id = ActionTableC.Id)
crappy quick sql syntax
Is this what you were alluding to in the answer below? A snapshot of what that could potentially look like:
Your question is a little unclear, but it looks like you should either have a (denormalized) value column in each action table, or have an artificial key in the value table that is keyed to by each of the seperate action tables.