Assign unique ID to duplicates in Access - sql

Question

I had a very big excel spreadsheet that I moved into Access to try to deal with it easier. I'm very much a novice. I'm trying to use SQL via Access.
I need to assign a unique identifier to duplicates. I've seen people use DENSE_RANK in SQL but I can't get it to work in Access.
Here's what I'm trying to do: I have a large amount of patient and sample data (20k rows). My columns are called FULL_NAME, SAMPLE_NUM, and DATE_REC. Some patients have come in more than once and have multiple samples. I want to give each patient a unique ID that I want to call PATIENT_ID.
I can't figure out how to do this, aside from typing it out on each row. I would greatly appreciate help as I really don't know what I'm doing and there is no one at my work who can help.

Answer 1

To illustrate the previous answers' textual explanation, consider the following SQL action queries which can be run in an Access query window one by one or as VBA string queries with DAO's CurrentDb.Execute or DoCmd.RunSQL. The ALTER statements can be done in MSAcecss.exe.
Create a Patients table (make-table query)
SELECT DISTINCT s.FULL_NAME INTO myPatientsTable
FROM mySamplesTable s
WHERE s.FULL_NAME IS NOT NULL;
Add an autonumber field to new Patients table as a Primary Key
ALTER TABLE myPatientsTable ADD COLUMN PATIENT_ID AUTOINCREMENT NOT NULL PRIMARY KEY;
Add a blank Patient_ID column to Samples table
ALTER TABLE mySamplesTable ADD COLUMN PATIENT_ID INTEGER;
Update Patient_ID Column in Samples table using FULL_NAME field
UPDATE mySamplesTable s
INNER JOIN myPatientsTable p
ON s.[FULL_NAME] = p.[FULL_NAME]
SET s.PATIENT_ID = p.PATIENT_ID;
Maintain third-norm principles of relational databases and remove FULL_NAME field from Samples table
ALTER TABLE mySamplesTable DROP COLUMN FULL_NAME;
Then in a separate query, add a foreign key constraint on PATIENT_ID
ALTER TABLE mySamplesTable
ADD CONSTRAINT PatientRelationship
FOREIGN KEY (PATIENT_ID)
REFERENCES myPatientsTable (PATIENT_ID);

Answer 2

Sounds like FULL_NAME is currently the unique identifier. However, names make very poor unique identifiers and name parts should be in separate fields. Are you sure you don't have multiple patients with same name, e.g. John Smith?
You need a PatientInfo table and then the SampleData table. Do a query that pulls DISTINCT patient info (apparently this is only one field - FULL_NAME) and create a table that generates unique ID with autonumber field. Then build a query that joins tables on the two FULL_Name fields and updates a new field in SampleData called PatientID. Delete the FULL_Name field from SampleData.

Answer 3

The command to number rows in your table is [1]
ALTER TABLE MyTable ADD COLUMN ID AUTOINCREMENT;
Anyway as June7 pointed out it might not be a good idea to combine records just based on patient name as there might be duplicates. Better way will be treat each record as unique patient for now and have a way to fix patient ID when patient comes back. I would suggest to go this way:
create two new columns in your samples table
ID with autoincrement as per query above
patientID where you will copy values from ID column - for now they will be same. But in future they will diverge
copy columns patientID and patientName into separate table patients
now you can delete patientName column from samples table
add column imported to patients table to indicate, that there might be some other records that belong to this patient.
when patients come back you open his record, update all other info like address, phone, ... and look for all possible samples record that belong to him. If so, then fix patient id in those records.
Now you can switch imported indicator because this patient data are up to date.
After fixing patientID for samples records. You will end up with patients with no record in samples table. So you can go and delete them.

Answer 4

Unless you already have a natural key you will be corrupting this data when you run the distinct query and build a key from it. From your posting I would guess a natural key would be SAMPLE_NUM. Another problem is that if you roll up by last name you will almost certainly be combining different patients into one.