CASE...WHEN in WHERE clause in Postgresql

Question

My query looks like:

SELECT * 
FROM table 
WHERE t1.id_status_notatka_1 = ANY (selected_type)  
 AND t1.id_status_notatka_2 = ANY (selected_place) 

here I would like to add CASE WHEN so my query is:

    SELECT *  
    FROM table 
    WHERE t1.id_status_notatka_1 = ANY (selected_type)  
      AND t1.id_status_notatka_2    = ANY (selected_place) 
      AND CASE 
            WHEN t2.id_bank = 12 THEN t1.id_status_notatka_4 = ANY (selected_effect) 
         END

but it doesn't work. The syntax is good but it fails in searching for anything. So my question is - how use CASE WHEN in WHERE clause. Short example: if a=0 then add some condition to WHERE (AND condition), if it's not then don't add (AND condition)

Answer 1

No need for CASE EXPRESSION , simply use OR with parenthesis :

AND (t2.id_bank <> 12 OR t1.id_status_notatka_4 = ANY (selected_effect))

Answer 2

The accepted answer works, but I'd like to share input for those who are looking for a different answer. Thanks to sagi, I've come up with the following query, but I'd like to give a test case as well.

Let us assume this is the structure of our table

tbl
id   | type     | status
-----------------------
1    | Student  | t
2    | Employee | f
3    | Employee | t
4    | Student  | f

and we want to select all Student rows, that have Status = 't', however, We also like to retrieve all Employee rows regardless of its Status.

if we perform SELECT * FROM tbl WHERE type = 'Student' AND status = 't' we would only get the following result, we won't be able to fetch Employees

tbl
id   | type     | status
-----------------------
1    | Student  | t

and performing SELECT * FROM tbl WHERE Status = 't' we would only get the following result, we got an Employee Row on the result but there are Employee Rows that were not included on the result set, one could argue that performing IN might work, however, it will give the same result set. SELECT * FROM tbl WHERE type IN('Student', 'Employee') AND status = 't'

tbl
id   | type     | status
-----------------------
1    | Student  | t
3    | Employee | t

remember, we want to retrieve all Employee rows regardless of its Status, to do that we perform the query

SELECT * FROM tbl WHERE (type = 'Student' AND status = 't') OR (type = 'Employee')

result will be

table
id   | type     | status
-----------------------
1    | Student  | t
2    | Employee | f
3    | Employee | t