How to select datas that doesnt match in another column

Question

So i have this table A:

color        ID       MODEL
-----------------------------
red        | 10   |   HONDA
blue       | 10   |   TOYOTA
red        | 15   |            


        

Answer 1

I think your expected result should just be red 15. Red 30 would not qualify because of yellow 30, which shares the same id. Check out my code:

SELECT t.id, t.color
FROM t
INNER JOIN
(SELECT id
 FROM t
 GROUP BY id
 HAVING COUNT(*) = 1) sub
ON t.id = sub.id
WHERE color = 'red'
OR color = 'blue'

Answer 2

This query returns all the IDs where the COLOR is red or blue but not both.

select id , color
from  your_table 
where color in ('red', 'blue')
and id in (
    select id 
    from   your_table 
    where color in ('red', 'blue')
    group by id 
    having count(*) = 1) 

Answer 3

Something like this

SELECT * 
FROM   yourtable 
WHERE  id IN (SELECT id 
              FROM   youtable 
              GROUP  BY id 
              HAVING Count(case when color IN ( 'red', 'blue' ) then 1 end) = 1) 

Answer 4

or using an anti join

select t1.color, t1.id 
from 
    tableA t1
left outer join 
     tableA t2 on t2.id = t1.id and t2.color != t1.color 
where 
 t1.color in ('red', 'blue')
and t2.color is null

Answer 5

Use NOT EXISTS to find rows with matching id but different colors:

select *
from yourtable a
where a.color IN ('red', 'blue')
  and not exists (
    select 1
    from yourtable b
    where a.id = b.id
      and b.color NOT IN ('red', 'blue')
    )

Notes:

• for efficient lookup consider adding indexes ( more distinct values means higher efficiency of tree traversal )
• consider normalizing your data with additional dictionary color table

Answer 6

Removed the previous answer. Tested this and it is working.

WITH tbl
AS (SELECT
  color,
  id
FROM TABLE1
WHERE color IN ('red', 'blue')
)
SELECT
  t1.color,
  t1.id
FROM tbl t1
LEFT JOIN tbl t2
  ON t1.id = t2.id
  AND t1.color <> t2.color
WHERE t1.id IS NULL
OR t2.id IS NULL