CODEWITHSUNDEEP
sqlpostgresql
bla
bla

Reputation: 1055

How i can return records there are not null only if a column have a determined value

I need to make a query that verify:

if type_answer is equal to Multipla Escolha so i only have to return the records that are not null in correct_answer_description_id If the type_answer is not equal to Multipla Escolha, don’t make this rule.

So, i try this way:

SELECT * FROM book_unit_question
WHERE book_unit_id = 2 
AND status = false
CASE WHEN type_answer = 'Multipla Escolha' THEN
correct_answer_description IS NOT NULL

but i'm getting: 

ERROR:  syntax error at or near "CASE"

Upvotes: 0

Views: 31

Answers (2)

Belayer
Belayer

Reputation: 14936

Getting rid of the negative yields negative construct "type_answer is not equal to Multipla Escolha, don’t make this rule" by rephrasing "type answer equal Multipla Escolha then apply this rule. Also applying "only return the records that are not null in correct_answer_description_id". We arrieve at: 

select * 
  from book_unit_question
 where book_unit_id = 2 
   and status = false
   and type_answer = 'Multipla Escolha' 
   and correct_answer_description is not null;

Upvotes: 0

Chris94
Chris94

Reputation: 312

I don't think CASE is the easiest approach here. Can you try the re-written query below? 

SELECT * FROM book_unit_question
WHERE book_unit_id = 2 
AND status = false
AND (type_answer is null or type_answer != 'Multipla Escolha' or
correct_answer_description IS NOT NULL)

Upvotes: 1

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