Best practice to avoid duplicate data entries in a mysql DB

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VB

MySQL

I've looked around on various websites in search for a "best practice" method when trying to avoid duplicate entries in a MySQL DB.

I did find basic information on how to detect duplicate entries, but I still fail to find substantial information on how to implement a complete solution to detect for duplication and then control the execution process within a stored procedure.

I believe this is where I will now have to explain myself better:

I collect patient demographic information and insert that into a MySQL database. The information is specific to:

Patient
|
-- Patient Details (table)
|
-- Patient Contact Details (table)
|
-- Patient Address Details - Street & Postal (table)
|
-- Patient Medical Insurance Details (table)
|
-- Patient Next of Kin Details (table)
|
-- Patient Employer Details (table)

Validation is done on "Patient Details" (First Name, Last Name, SSN, DOB, etc) with the following SP:

DELIMITER $$

CREATE DEFINER=`rootuser`@`%` PROCEDURE `SP_patAddDetails`(
/*IN pFileNo 		VARCHAR(11),*/
IN pKey 		VARCHAR(1),
IN pTitle 		VARCHAR(15),
IN pFirstName 		VARCHAR(30),
IN pInitials 		VARCHAR(5),
IN pSurname 		VARCHAR(30),
IN pIDNo 		VARCHAR(15),
IN pDOB 		VARCHAR(10),
IN pGender  		VARCHAR(8),
IN pLanguage 		VARCHAR(15),
IN pOccupation 		VARCHAR(30),
IN pDependantCode 	VARCHAR(2),
IN pRelationship 	VARCHAR(15),
IN pMemNo 		VARCHAR(20),
IN pDateOpened      VARCHAR(10)
)
BEGIN
START TRANSACTION;

INSERT INTO patDetails(patKey, patTitle, patFirstName, patInitials, 
                       patSurname, patIDNo, patDOB, patGender, patLanguage,
                       patOccupation, patDependantCode, patRelationship, 
                       patMemNo, patDateOpened, patUpdated) 
 
 /*
INSERT INTO patDetails(patFileNo, patKey, patTitle, patFirstName, patInitials, 
                       patSurname, patIDNo, patDOB, patGender, patLanguage,
                       patOccupation, patDependantCode, patRelationship, 
                       patMemNo, patUpdated, patDateOpened)
*/
  
  
 /*                      
to avoid duplicate entries during the patient add process 
   check to see if patient already exist in the patDetails table
*/		


       
        SELECT * FROM (SELECT pKey, pTitle, pFirstName, pInitials, 
                              pSurname, pIDNo, pDOB, pGender, pLanguage, 
                              pOccupation, pDependantCode, pRelationship, 
                              pMemNo, pDateOpened, now()) AS tmp
                              
/*        
SELECT * FROM (SELECT pFileNo, pKey, pTitle, pFirstName, pInitials, 
                              pSurname, pIDNo, pDOB, pGender, pLanguage, 
                              pOccupation, pDependantCode, pRelationship, 
                              pMemNo, now()) AS tmp, pDateOpened
*/
        
        WHERE NOT EXISTS (
			SELECT patTitle, patFirstName, patInitials, patSurname, patDOB, patMemNo
			FROM   patDetails 
			WHERE  patTitle = pTitle
			AND    patFirstName = pFirstName
			AND    patInitials = pInitials
			AND    patSurname = pSurname
            AND    patDOB = pDOB
            AND    patMemNo = pMemNo
        ) 
        LIMIT 1;    

 /*               
        WHERE NOT EXISTS (
			SELECT patFileNo, patKey, patTitle, patFirstName, patInitials, patSurname
			FROM   patDetails 
			WHERE  patFileNo = pFileNo
			AND    patKey = pKey
			AND    patTitle = pTitle
			AND    patFirstName = pFirstName
			AND    patInitials = pInitials
			AND    patSurname = pSurname
        ) 
        LIMIT 1;  
*/

COMMIT;


SELECT LAST_INSERT_ID()

COMMIT;
END

Currently I am controlling the validation process inside my VB.net Forms application by checking to see if I get a new database ID returned. If a new ID is returned I know that validation passed, the patient details were written to the DB and I get a new DB ID which I can then use as my foreign key during the rest of the process. (I am happy to edit the post to remove all the remarked code lines, things I tried, if it posses any reading difficulty)

I want to believe that there is a much more logical method of doing this within MySQL rather than doing it external, but I don't seem to find the information I need to achieve this...maybe it is meant to be done from an application rather from inside MySQL (which I want to be wrong about).

Regards,
T

What I have tried:

In the Stored Procedure there are commented lines of code of things I've tried but this is still a process which it controlled outside of MySQL.
-edit: grammar