数据仓库事实表外键生成

Question

I am pretty new to data warehouse designing. I have a database like below.

https://webpages.charlotte.edu/mirsad/itcs6265/group1/domain.html

I am planning to create a simple data warehouse like below.

But the problem I am facing now is I don't have ClientId and LoanId in the Fact table. Because in the original database it was lnked via Account table. I am trying to achieve this via SQL server. Can someone show me the direction how to approach this.

Answer 1

If you want to create the FactTransaction fact table you don't need the Loan because it represents a fact so Transaction and Loan are two differnt actions like mentioned in the data dictionary:

TRANSACTIONS (TRANS) Each record describes one transaction on an account

LOANS Each record describes a loan granted for a given account

the design can be like below if we follow a separate context for each:

Datamart Transaction:

Datamart Loan:

The query to populate the FactTransaction is like below:

SELECT T.account_id AS TransactionID, C.client_id AS ClientID,
A.account_id AS AccountID
FROM Transactions AS T
LEFT JOIN Account AS A ON A.account_id=T.account_id
LEFT JOIN Disposition AS D ON A.account_id=D.account_id
LEFT JOIN Client AS C ON C.client_id=D.client_id

AccountID, TransactionID, ClientID represent a composite key to uniquely identify the tuple transaction in a the fact table.

The query to populate the FactLoan is like below:

 SELECT L.account_id AS LoanID, C.client_id AS ClientID,
A.account_id AS AccountID
    FROM Loan AS L
    LEFT JOIN Account AS A ON A.account_id=A.account_id
    LEFT JOIN Disposition AS D ON A.account_id=D.account_id
    LEFT JOIN Client AS C ON C.client_id=D.client_id

AccountID, LoanID, ClientID represent a composite key to uniquely identify the tuple transaction in a the fact table.

Do not forget to implement the DimDate.