Question

我有这张桌子：

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

我想找到超过2种产品的供应商。但只有select和where，没有group by。有什么建议吗？

Answer 1

为什么你不想使用group by超出我，但这可能有用：

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

请记住，该组是为这样的东西制作的，应该使用。

Answer 2

在通常的parts and suppliers database中，此relvar名为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而不使用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 3

;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);

Answer 4

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

Answer 5

带子查询的

：

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

只在sql中使用select而不是group by

5 个答案: