How do i...check for duplicate entries on mysql DB while adding new row

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)
)
BEGIN
START TRANSACTION;

INSERT INTO patDetails(patFileNo, patKey, patTitle, patFirstName, patInitials, 
                       patSurname, patIDNo, patDOB, patGender, patLanguage,
                       patOccupation, patDependantCode, patRelationship, 
                       patMemNo, patUpdated) 
/* to avoid duplicate entries during the patient add process 
   check to see if patient already exist in the patDetails table*/		
        
        SELECT * FROM (SELECT pFileNo, pKey, pTitle, pFirstName, pInitials, 
                              pSurname, pIDNo, pDOB, pGender, pLanguage, 
                              pOccupation, pDependantCode, pRelationship, 
                              pMemNo, now()) AS tmp
        
        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;
                
/*        VALUES (pAccKey, pKey, pTitle, pFirstName, pInitials, pSurname, pIDNo,
                pDOB, pGender, pLanguage, pOccupation, pDependantCode,
                pRelatioship, pMemNo, NOW);
                SELECT LAST_INSERT_ID()
*/
COMMIT;

SELECT LAST_INSERT_ID()

COMMIT;
END