SQL View to find missing values, should be simple [closed]

Question

Closed. This question does not meet Stack Overflow guidelines. It is not currently accepting answers.

---

Questions asking for code must demonstrate a minimal understanding of the problem being solved. Include attempted solutions, why they didn't work, and the expected results. See also: Stack Overflow question checklist

Closed 8 years ago.

Improve this question

I have two tables with a common id, table1 has a task numbers column and table2 has documents column each task can have multiple documents. I'm trying to find all task numbers that don't have a specific document

Fake data:

SELECT * FROM table1
id  tasknumber
1   3210-012
2   3210-022
3   3210-032

SELECT * FROM table2
id  document
1   revision1
1   SB
1   Ref
2   revision1
2   Ref
3   revision1
3   SB

But how would I find tasknumbers which don't have a document named SB?

Answer 1

SELECT t1.tasknumber
FROM   table1 t1
LEFT   JOIN table2 t2 ON t2.id = t1.id AND t2.document = 'SB'
WHERE  t2.id IS NULL;

There are basically four techniques:

• Select rows which are not present in other table

Answer 2

select t1.tasknumber from table1 t1
where not exists 
     (select 1 from table2 t2 where t1.id = t2.id and t2.document = 'SB')

Answer 3

select
    tasknumber
from 
    table1
where
    not exists (select 1
                  from table2
                 where table1.id = table2.id
                       and table2.document = 'SB');

or

select
    tasknumber
from 
    table1
where
    id not in (select id
                 from table2 
                where document = 'SB');

Answer 4

Use this:

SELECT TASKNUMBER 
FROM TABLE1
WHERE ID NOT IN (SELECT DISTINCT ID FROM TABLE 2 where document = 'SB')