在关系数据库中表示类似规则输入的最佳方式是什么？

Question

I am designing a rules database, which takes a number of inputs and determines the appropriate output.

There is a set of ~20 input types that are very similar (can be represented with Id, Value) which all drive a set ~20 output types. Each input type has a number of possible values. Each output type has a number of possible values as well.

An example rule would be InputTypeA + InputTypeB determines OutputTypeA or InputTypeA determines OutputTypeB . n input types can drive an output, but currently the maximum number is 3.

1. What is the best way to store the input values? I am considering either:

• Storing in one table, with a InputType table FK'd to determine the type of the input value (they will all be strings from a db type perspective).
• Storing each input type in a seperate table.

2. How can I represent the relationships? I could have a separate table for each relationship, but this system should be as flexible as possible. I'm concerned that will be a large number of tables, and make it difficult to add new rules.

Answer 1

I would think of this as 3 major concepts.

Condition : what needs to be true for a rule to fire? Rule : when a rule fires, which results are true? Result : which outputs fire, and with which values?

Conditions are modelled as one or more inputs with their values (your example uses InputTypeA + InputTypeB so I assume a rule has one or more qualifying inputs).

Results are modelled as one or more output, with their values.

Specifically:

Condition
-----------
ID
RuleID
InputType
InputValue

Rule
----
ID

Result
-------
ID
RuleID
OutputType
OutputValue

If there is more logic to input types and output types, you can create a lookup table with a foreign key relationship.

Example might be:

Condition

ID RuleID InputType         InputValue
1       1 DrivingIn30zone            1
2       1 CurrentSpeed              40

Rule

ID   Name
1    Don't break the speed limit

Result
ID    RuleID    OutputType    OutputValue
1.         1     SetSpeed              29

You would then search for conditions which match your current input values to see what the output states are: