CASE expression in WHERE clause Postgresql - postgresql

Question

I have been struggling to figure out how to put a CASE expression in the WHERE clause using PostgreSQL. I need to convert the string to a date (as seen in line 3). This works fine. When I try to pull CURRENT_DATE in the WHERE clause I run into errors. Is this the best way to do this? Any suggestions would be very much welcomed.
SELECT
CASE WHEN
multi_app_documentation.nsma1_code = 'DATE' THEN TO_DATE(multi_app_documentation.nsma1_ans, 'MMDDYYYY') END AS "Procedure Date",
' ' AS "Case Confirmation Number",
ip_visit_1.ipv1_firstname AS "Patient First",
ip_visit_1.ipv1_lastname AS "Patient Last",
visit.visit_sex AS "Patient Gender",
TO_CHAR(visit.visit_date_of_birth, 'MM/DD/YYYY') AS "DOB",
visit.visit_id AS "Account Number",
visit.visit_mr_num AS "MRN",
' ' AS "Module",
' ' AS "Signed off DT",
CASE WHEN
multi_app_documentation.nsma1_code = 'CRNA' THEN multi_app_documentation.nsma1_ans END AS "Primary CRNA",
' ' AS "Secondary CRNA",
' ' AS "Primary Anesthesiologist",
' ' AS "Secondary Anesthesiologist",
' ' AS "Canceled Yes/No"
FROM
multi_app_documentation
INNER JOIN ip_visit_1 ON multi_app_documentation.nsma1_patnum = ip_visit_1.ipv1_num
INNER JOIN visit ON ip_visit_1.ipv1_num = visit.visit_id
WHERE
CASE
WHEN ( multi_app_documentation.nsma1_code = 'DATE' AND TO_DATE( multi_app_documentation.nsma1_ans, 'MMDDYYYY' ) = CURRENT_DATE END )
AND multi_app_documentation.nsma1_ans IS NOT NULL
ORDER BY
ip_visit_1.ipv1_lastname ASC

Answer 1

Your parentheses are unbalanced. Also, you don't even need a CASE expression in the WHERE clause. Use this version:
WHERE
multi_app_documentation.nsma1_code = 'DATE' AND
TO_DATE(multi_app_documentation.nsma1_ans, 'MMDDYYYY') = CURRENT_DATE
In addition, it is undesirable to store text dates in the nsma1_ans column. It would be better to use a bona-fide date column. If you must store the dates as text, then at least use the format YYYY-MM-DD, which then could simply be cast to date using nsma1_ans::date.