SQL query to filter by specific date criteria - sql

Question

SQL query to filter by specific date criteria
SQL Server Management Studio V17.7
Question: I am looking for guidance related to a view on how to select records where the Start_Date falls between a defined date range when either the Admit_Status = 1 or Admit_Status = 0 as shown below:
Criteria should be something like: if admit status = 1 then dbo.PT_ASSIGNMENT.START_DATE >= referral_date to ifnull dbo.PT_ADMISSION.TERMINATION_DATE then now() else dbo.PT_ADMISSION.TERMINATION_DATE or if admit status = 0 then start_date >= referral_date to ifnull dbo.PT_ADMISSION.PROSPECT_TERM_DATE then now() else dbo.PT_ADMISSION.PROSPECT_TERM_DATE
My SQL query (View) excluding the above question:
SELECT dbo.RES_BASIC.RESOURCE_ID,
dbo.PT_ADMISSION.ADMISSION_ID,
dbo.PT_ASSIGNMENT.START_DATE,
(CASE PT_ADMISSION.PROSPECT_ADMIT_DATE WHEN NULL THEN PT_ADMISSION.ADMIT_DATE ELSE PT_ADMISSION.PROSPECT_ADMIT_DATE END) AS REFERRAL_DATE,
dbo.PT_ADMISSION.ADMIT_DATE,
dbo.PT_ADMISSION.PROSPECT_ADMIT_DATE,
dbo.PT_ADMISSION.PROSPECT_TERM_DATE,
dbo.PT_ADMISSION.TERMINATION_DATE,
CASE WHEN PT_ADMISSION.ADMIT_DATE IS NOT NULL THEN 1 ELSE 0 END AS ADMIT_STATUS,
dbo.PT_BASIC.PATIENT_CODE,
dbo.RES_BASIC.NAME_FULL
FROM dbo.PT_BASIC
INNER JOIN dbo.PT_STATUS
ON dbo.PT_BASIC.PATIENT_ID = dbo.PT_STATUS.PATIENT_ID
INNER JOIN dbo.A_PATIENT_STATUS
ON dbo.PT_STATUS.ADMIN_SET_ID = dbo.A_PATIENT_STATUS.ADMIN_SET_ID
AND dbo.PT_STATUS.STATUS_CODE = dbo.A_PATIENT_STATUS.STATUS_CODE
INNER JOIN dbo.O_DATASET
ON dbo.PT_BASIC.DATASET_ID = dbo.O_DATASET.DATASET_ID
INNER JOIN dbo.PT_ADMISSION
ON dbo.PT_BASIC.PATIENT_ID = dbo.PT_ADMISSION.PATIENT_ID
AND dbo.PT_STATUS.ADMISSION_ID = dbo.PT_ADMISSION.ADMISSION_ID
INNER JOIN dbo.PT_ASSIGNMENT
ON dbo.PT_BASIC.PATIENT_ID = dbo.PT_ASSIGNMENT.PATIENT_ID
INNER JOIN dbo.A_ASSIGNMENT_TYPE
ON dbo.PT_ASSIGNMENT.ADMIN_SET_ID = dbo.A_ASSIGNMENT_TYPE.ADMIN_SET_ID
AND dbo.PT_ASSIGNMENT.ASSIGNMENT_TYPE = dbo.A_ASSIGNMENT_TYPE.TYPE_ID
INNER JOIN dbo.RES_BASIC
ON dbo.PT_ASSIGNMENT.RESOURCE_ID = dbo.RES_BASIC.RESOURCE_ID
WHERE (dbo.O_DATASET.DATASET_NAME = 'XXXXXXXXXX')
AND (dbo.A_ASSIGNMENT_TYPE.DESCRIPTION = 'REFERRING PHYSICIAN')
GROUP BY dbo.RES_BASIC.NAME_FIRST + ' ' + dbo.RES_BASIC.NAME_LAST,
dbo.RES_BASIC.RESOURCE_ID,
dbo.PT_ADMISSION.ADMISSION_ID,
dbo.PT_BASIC.PATIENT_CODE,
dbo.PT_ASSIGNMENT.START_DATE,
dbo.PT_ADMISSION.PROSPECT_TERM_DATE,
dbo.PT_ADMISSION.PROSPECT_ADMIT_DATE,
dbo.PT_ADMISSION.TERMINATION_DATE,
dbo.PT_ADMISSION.ADMIT_DATE,
dbo.RES_BASIC.NAME_FULL

Answer 1

You can put pretty much any "if" into a condition with simple AND and OR use.
I am having a hard time mentally parsing your "something like" portion, but to give a generic example.
IF A THEN B ELSE C
can be translated to (A AND B) OR (NOT A AND C)
Note: Bill Braskey's "comment" is also worth considering. If the conditional logic gets complicated enough, it can be less work for the database to UNION queries with simpler conditions. You'd still need the condition in one to be A AND B and the other to be NOT A AND C to apply the conditions appropriately, but you'd be simplifying from the overall condition (especially when you consider "C" could actually be a translation of IF D THEN E ELSE F.

Answer 2

Maybe just take the easy way out and write two queries with the separate requirements and do a union