按或分组-如何处理3张桌子

Question

SELECT c.urun_id, a.kat_adi, b.resim_yolu, b.sira, 
c.urun_sira, c.urun_adi
FROM kategoriler a,resimler b, urunler c 
where  a.kat_id=c.kat_id and c.urun_id=b.urun_id
order by c.urun_sira,b.sira

There are two record with urun_id = 17 . I want to return only one record. I have category , products , images tables. User has added 2 photos in images table where urun_id=17 .

But I want to show only one record which has minimum value in sira .

If the output of the query is

• 25 ~ pc ~ 3
• 17 ~ phone ~ 2
• 17 ~ phone ~ 4

Then, I want to return

• 17 ~ phone ~ 2

Answer 1

If I understood your question correctly, this should work,

SELECT c.urun_id, a.kat_adi, b.resim_yolu, min(b.sira),
       c.urun_sira, c.urun_adi
FROM kategoriler a,resimler b, urunler c
where a.kat_id=c.kat_id
and c.urun_id=b.urun_id
group by c.urun_id, a.kat_adi, b.resim_yolu,
       c.urun_sira, c.urun_adi
order by c.urun_sira,b.sira

Answer 2

In SQLServer2005+ use ROW_NUMBER function

 ;WITH cte AS
 (
  SELECT c.urun_id, a.kat_adi, b.resim_yolu, b.sira, 
         c.urun_sira, c.urun_adi, 
         ROW_NUMBER() OVER (PARTITION BY c.urun_id ORDER BY b.sira) AS rn
  FROM kategoriler a JOIN urunler c ON a.kat_id=c.kat_id
                     JOIN resimler b ON c.urun_id=b.urun_id
  )
  SELECT *
  FROM cte
  WHERE rn = 1
  ORDER BY urun_sira, sira

Other way

  SELECT c.urun_id, a.kat_adi, b.resim_yolu, b.sira, 
         c.urun_sira, c.urun_adi         
  FROM kategoriler a JOIN urunler c ON a.kat_id=c.kat_id
                     JOIN resimler b ON c.urun_id=b.urun_id  
  WHERE EXISTS (
                SELECT 1
                FROM resimler r
                WHERE b.urun_id = r.urun_id
                HAVING MIN(r.sira) = b.sira
                )
  ORDER BY c.urun_sira, b.sira