选择与另一列相关的唯一值

Question

I have a table like this:

╔════╦════════════╦══════════╗
║ id ║ project_id ║ document ║
╠════╬════════════╬══════════╣
║  1 ║     1      ║    3     ║
║  2 ║     1      ║    5     ║  
║  3 ║     2      ║    3     ║
║  4 ║     2      ║    4     ║
║  5 ║     3      ║    5     ║
║  6 ║     4      ║    2     ║
╚════╩════════════╩══════════╝

I want all project_id which do not have document = 5

In other words, I want this result:

╔════════════╗
║ project_id ║
╠════════════╣
║     2      ║
║     4      ║
╚════════════╝

Answer 1

Try this:

SELECT project_id
FROM mytable
GROUP BY project_id
HAVING COUNT(CASE WHEN document = 5 THEN 1 END) = 0

Demo here