Parsing Character String

I'm running into a couple of performance issues with regards to the parsing of a text string. We have a function that will take a comma delimited character string, parse out the individual values, and then populate a temp table with those values. The two issues are 1.) the parsing process is VERY slow and 2.) there's a max to how large the string can be - at some point it could easily be 8000 characters or more in length.



Here are the function and the stored procedure where it occurs:


CREATE FUNCTION [dbo].[Split](@String varchar(MAX), @Delimiter char(1))
RETURNS @Results TABLE (Item nvarchar(4000))
AS
BEGIN
DECLARE @INDEX INT
DECLARE @SLICE nvarchar(4000)
-- HAVE TO SET TO 1 SO IT DOESNT EQUAL ZERO
-- FIRST TIME IN LOOP
SELECT @INDEX = 1
WHILE @INDEX !=0
BEGIN
-- GET THE INDEX OF THE FIRST OCCURENCE OF THE SPLIT CHARACTER
SELECT @INDEX = CHARINDEX(@Delimiter,@STRING)
-- NOW PUSH EVERYTHING TO THE LEFT OF IT INTO THE SLICE VARIABLE
IF @INDEX !=0
SELECT @SLICE = LEFT(@STRING,@INDEX - 1)
ELSE
SELECT @SLICE = @STRING
-- PUT THE ITEM INTO THE RESULTS SET
INSERT INTO @Results(Item) VALUES(@SLICE)
-- CHOP THE ITEM REMOVED OFF THE MAIN STRING
SELECT @STRING = RIGHT(@STRING,LEN(@STRING) - @INDEX)
-- BREAK OUT IF WE ARE DONE
IF LEN(@STRING) = 0 BREAK
END
RETURN
END

--------------------

...and the stored procedure:


CREATE PROCEDURE [dbo].[RPTPatientAnalysis]
(
@stateList CHAR(2),
@employerIdList VARCHAR(4000),
@payerIdList VARCHAR(4000)
)
AS
SELECT
p.PAT_ID,
p.PAT_FirstName,
ISNULL(p.PAT_MiddleName,'') AS PAT_MiddleName,
p.PAT_LastName,
p.PAT_Gender,
CONVERT(VARCHAR(10),p.PAT_DOB,101) AS DOB,
p.PAT_AddressStreet1,
ISNULL(p.PAT_AddressStreet2,'') AS PAT_AddressStreet2,
p.PAT_AddressCity,
p.PAT_AddressStateProvince,
p.PAT_AddressPostalCode,
ISNULL(p.PAT_EmailAddress,'') AS PAT_EmailAddress,
p.PAT_PhoneNumber,
ISNULL(e.EMPLOYER_Name,'<Unknown>') AS EMPLOYER_Name,
ISNULL(p.PAT_OtherEmployerName,'') AS PAT_OtherEmployerName,
ISNULL(p.PAT_Comment,'') AS PAT_Comment,
ISNULL(p.PAT_PrimCareProv_PRIMCP_ID,'') AS PAT_PrimCareProv_PRIMCP_ID,
ISNULL(p.PAT_PrimCareProvAllowNotification,0) AS PAT_PrimCareProvAllowNotification,
ISNULL(p.PAT_PrimCareProvFullName,'') AS PAT_PrimCareProvFullName,
ISNULL(p.PAT_DoNotMail,0) AS PAT_DoNotMail,
ISNULL(p.PAT_UnderAgePermission,0) AS PAT_UnderAgePermission,
p.PAT_LastEandMCodingDateTime,
p.PAT_Desceased,
p.PAT_PCP_ID,
p.PAT_LastUpdatedDateTime,
ISNULL(p.PAT_PCPRecordType,0) AS PAT_PCPRecordType,
ISNULL(p.PAT_EnableEmailMarketing,0) AS PAT_EnableEmailMarketing,
ISNULL(p.PAT_EnablePortal,0) AS PAT_EnablePortal,
ISNULL(p.PAT_PortalID,0) AS PAT_PortalID,
ISNULL(e2.EMPLOYER_Name,'') AS EMPLOYER_Name,
ISNULL(p.PAT_OtherEmployerName,'') AS PAT_OtherEmployerName,
pcp.PRIMCP_ID,
ISNULL(pcp.PRIMCP_ADDR_ID,'') AS PRIMCP_ADDR_ID,
ISNULL(pcp.PRIMCP_ClinicName,'') AS PRIMCP_ClinicName,
ISNULL(pcp.PRIMCP_PhysicianFullname,'') AS PRIMCP_PhysicianFullname,
pcp.PRIMCP_DateDeactivated,
ISNULL(pcp.PRIMCP_Phone_MedicalRecordFax,'') AS PRIMCP_Phone_MedicalRecordFax,
ISNULL(pcp.PRIMCP_Phone_Voice,'') AS PRIMCP_Phone_Voice,
ISNULL(pcp.PRIMCP_MedicalRecords_Street1,'') AS PRIMCP_MedicalRecords_Street1,
ISNULL(pcp.PRIMCP_MedicalRecords_Street2,'') AS PRIMCP_MedicalRecords_Street2,
ISNULL(pcp.PRIMCP_MedicalRecords_City,'') AS PRIMCP_MedicalRecords_City,
ISNULL(pcp.PRIMCP_MedicalRecords_State,'') AS PRIMCP_MedicalRecords_State,
ISNULL(pcp.PRIMCP_MedicalRecords_Zip,'') AS PRIMCP_MedicalRecords_Zip,
ISNULL(pcp.PRIMCP_Street1,'') AS PRIMCP_Street1,
ISNULL(pcp.PRIMCP_Street2,'') AS PRIMCP_Street2,
ISNULL(pcp.PRIMCP_City,'') AS PRIMCP_City,
ISNULL(pcp.PRIMCP_State,'') AS PRIMCP_State,
ISNULL(pcp.PRIMCP_Zip,'') AS PRIMCP_Zip,
ISNULL(pcp.PRIMCP_DoNotFax,0) AS PRIMCP_DoNotFax,
pati.PATINS_InsuranceTypeID,
ISNULL(pati.PATINS_Account,'') AS PATINS_Account,
ISNULL(pati.PATINS_Group,'') AS PATINS_Group,
ISNULL(pati.PATINS_CopayType,'') AS PATINS_CopayType,
ISNULL(pati.PATINS_CopayAmount,0) AS PATINS_CopayAmount,
ISNULL(pati.PATINS_CollectFullAmount,0) AS PATINS_CollectFullAmount,
ISNULL(pati.PATINS_EmployerPays,0) AS PATINS_EmployerPays,
ISNULL(pati.PATINS_ZeroScreenCopay,0) AS PATINS_ZeroScreenCopay,
ISNULL(pati.PATINS_ZeroVaccineCopay,0) AS PATINS_ZeroVaccineCopay,
ISNULL(pati.PATINS_NonPar,0) AS PATINS_NonPar,
ISNULL(pati.PATINS_MedicarePlan,0) AS PATINS_MedicarePlan,
ISNULL(ipcl.INSPCAT_Description,'') AS INSPCAT_Description,
ISNULL(ip.INSP_Name,'') AS INSP_Name,
ISNULL(ip.INSP_ChargeFullPrice,0) AS INSP_ChargeFullPrice,
ISNULL(ip.INSP_CopayApplies,0) AS INSP_CopayApplies,
CONVERT(VARCHAR(10),ip.INSP_DeactivatedDate,101) AS INSP_DeactivatedDate,
ISNULL(ip.INSP_EligibilityActive,0) AS INSP_EligibilityActive,
CONVERT(VARCHAR(10),ip.INSP_PromoStartDate,101) AS INSP_PromoStartDate,
CONVERT(VARCHAR(10),ip.INSP_PromoEndDate,101) AS INSP_PromoEndDate
FROM dbo.patient AS p
LEFT JOIN dbo.Employer AS e ON p.PAT_EMPLOYER_ID = e.EMPLOYER_ID
LEFT JOIN dbo.Employer AS e2 ON p.PAT_SecondaryEMPLOYER_ID = e2.EMPLOYER_ID
LEFT JOIN dbo.PrimaryCareProvider AS pcp ON p.PAT_PCP_ID = pcp.PRIMCP_ID
LEFT JOIN dbo.PatientInsurance AS pati ON p.PAT_ID = pati.PATINS_PAT_PERS_ID AND PATINS_InsuranceTypeID = 1
LEFT JOIN dbo.InsurancePayer AS ip ON pati.PATINS_INSP_ID = ip.INSP_ID
LEFT JOIN dbo.InsurancePayerCategoryLookup AS ipcl ON ip.INSP_INSPCAT_ID = ipcl.INSPCAT_ID
WHERE p.PAT_AddressStateProvince IN (SELECT Item FROM dbo.SplitVarcharMax(@stateList,','))
AND PAT_EMPLOYER_ID IN (SELECT Item FROM dbo.SplitVarcharMax(@employerIdList,','))
AND pati.PATINS_INSP_ID IN (SELECT Item FROM dbo.SplitVarcharMax(@payerIdList,','))



Is there a faster / more efficient way to accomplish the above?


Any insight would be appreciated!!