You should put your fields directly in the SELECT (the LOAD is unnecessary (and so is the SQL if all you are doing is a SELECT)
Example:
TableName:
SELECT t1.Field1,
t2.Field2,
t3.Field3
FROM Table1 t1
LEFT JOIN Table2 t2
ON t1.t2id = t2.t2id
LEFT JOIN Table3 t3
ON t2.t3id = t3.t3id;
So yours would look something like (I made some edits to your field load based on assumptions on what might be in those, so you may need to cast/write them differently than in Qlik):
TableName:
SELECT
CAST(ServiceDate AS DATE) as "Date",
PatientId as ENC.PATIENTID,
CPT.Cpt as ENC.CPT,
DOC.UserName as RenderingPhysician,
Account as ENC.ITEMTYPE,
Unit as ENC.UNITS,
PRAC.PracticeName,
EncounterId,
CPT.CptCategory as ENC.CPTCATEGORY,
CAST(PatientId AS VARCHAR) + DOC.UserName + ServiceDate as Visits
FROM [DataMart.dbo.patientaccountreport PA
LEFT JOIN [DataMart].[dbo].[patientaccountcpt] CPT
ON CPT.EncounterCodeId = PA.EncounterCodeId
LEFT JOIN [DataMart].[dbo].[patientaccountuser] DOC
ON DOC.UserId = PA.RenderingId
LEFT JOIN [DataMart].[dbo].[patientaccountpractice] PRAC
ON PRAC.PracticeId = PA.PracticeId
WHERE [TransactionDate] <= '04-30-2018';
