Pull records for Audit Trail

Question

I am implementing audit trail in my application. I followed this and this created History table the tables that only needs to be audited.

I have a following tables to store the Patient information.

TenantId represent each tenant data, since its a multitenant application

Person and Patient table

Person

Id, TenantId, FirstName, LastName, DOB, Mobile, Email,AddedBy,UpdatedBy, IsDeleted

Patient

Id, PatientIDentifier, IsOP, CanSendSMS, AddedBy, UpdatedBy, IsDeleted

Also another table

Appointment

Id, PatientId, AppointmentDate, DoctorId, Price, AddedBy, UpdatedBy

AUDIT HISTORY TABLE STRUCTURE

PersonHistory

AuditId,Id, FirstName, LastName, DOB, AddedBy, UpdatedBy, AuditUserId, AuditDate, Action

Here Action represents A(ADD)/U(update)/D(delete)

The same structure has been created for Patient, Appointment

Now I got triggers to insert into History table whenever add/delete/update happens.

Now I got the data available in the audit history table.

I have to write a query for two requirements.

1. Get all the records for a perticular patient. I need to pull all the records from PatientHostory, AppointmentHistory, PersonHistory by using a PatientId . How do we write SQL that takes more records from same table for given id? UNION or JOIN ?

2. I need to take all the records from all the HistoryTable for the supplied AuditUser Id .

How can i write a query for this?

Answer 1

You would UNION the log data, also consider adding a HistoryType column to indicate which table it refers too

SELECT AuditId, Id, FirstName, LastName, DOB, AddedBy, UpdatedBy, 
       AuditUserId, AuditDate, Action, 'Person' HistoryType
FROM PersonHistory ph
JOIN Person p ON ph.id = p.id 
UNION ALL
SELECT AuditId,Id, FirstName, LastName, DOB, AddedBy, UpdatedBy, 
       AuditUserId, AuditDate, Action, 'Patient' HistoryType
FROM PatientHistory
UNION ALL    
SELECT AuditId,Id, FirstName, LastName, DOB, AddedBy, UpdatedBy, 
       AuditUserId, AuditDate, Action, 'Appointment' HistoryType
FROM AppointmentHistory

Turning the above into a VIEW would allow you to further query the data more easily

SELECT * FROM vAuditHistory
WHERE AuditUserId = 1234

If you need to get information from the 'originating' data ie PatientId s then again using the view you could do something along the lines of

DECLARE @PatientId VARCHAR(10) = '12345ABCDE'

SELECT h.*, p.PatientId
FROM vAuditHistory h
JOIN Patient pt ON pt.id = h.id
WHERE h.HistoryType = 'Patient'
AND pt.PatientId = @PatientId
UNION ALL
SELECT h.*, a.PatientId
FROM vAuditHistory h
JOIN Appointment a t ON a.id = h.id
WHERE h.HistoryType = 'Appointment'
AND pt.PatientId = @PatientId

or without the view

SELECT h.*, p.PatientId
FROM PatientHistory h
JOIN Patient pt ON pt.id = h.id
WHERE pt.PatientId = @PatientId
UNION ALL
SELECT h.*, a.PatientId
FROM AppointmentHistory h
JOIN Appointment a t ON a.id = h.id
WHERE pt.PatientId = @PatientId

Creating the above as an inline function would probably be useful