只使用SQL，而不是選擇組由

Question

我有這個表：

supplier | product | qty 
-------------------------- 
    s1  | p1 | 300 
    s1  | p2 | 90 
    s2  | p3 | 89 

我想找到供應商超過2種產品。 但只有選擇和在哪裏，沒有group by。任何建議？

Answer 1

爲什麼你想不使用組超越我，但是這可能工作：

SELECT Supplier FROM table outer WHERE 
    (
    select count(Products) from table inner 
    where inner.Supplier = outer.Supplier 
) > 2 

請記住，該組由爲東西做出這樣的，應該被使用。

Answer 2

;WITH T AS 
(
SELECT *, 
     COUNT(*) OVER (PARTITION BY S) AS Cnt 
FROM YourTable 
) 
SELECT DISTINCT S 
FROM T 
WHERE Cnt > 2 

Answer 3

在平時parts and suppliers database，這個relvar名爲SP：

SELECT DISTINCT T1.SNO 
    FROM SP AS T1 
      JOIN SP AS T2 
      ON T1.SNO = T2.SNO 
       AND T2.PNO <> T1.PNO 
      JOIN SP AS T3 
      ON T1.SNO = T3.SNO 
       AND T3.PNO <> T1.PNO 
       AND T3.PNO <> T2.PNO; 

注意到，您可以使用HAVING沒有GROUP BY：

SELECT DISTINCT T1.SNO 
    FROM SP AS T1 
WHERE EXISTS (
       SELECT 1 
       FROM SP AS T2 
       WHERE T2.SNO = T1.SNO 
       HAVING COUNT(*) > 2 
      ); 

Answer 4

與子查詢：

select distinct supplier 
from table a 
where (select count(*) 
     from table b 
     where b.supplier = a.supplier and b.product <> a.product 
     ) > 1 

Answer 5

;WITH 
    sequenced_data AS 
(
    SELECT 
    supplier, 
    ROW_NUMBER() OVER (PARTITION BY supplier ORDER BY product) AS supplier_product_ordinal 
    FROM 
    YourTable 
) 
SELECT 
    supplier 
FROM 
    sequenced_data 
WHERE 
    supplier_product_ordinal = 3 

但我希望它比使用GROUP BY更慢。

SELECT DISTINCT 
    supplier 
FROM 
    yourTable 
WHERE 
     EXISTS (SELECT * FROM yourTable AS lookup WHERE supplier = yourTable.supplier AND product < yourTable.product) 
    AND EXISTS (SELECT * FROM yourTable AS lookup WHERE supplier = yourTable.supplier AND product > yourTable.product);