Question

我正在尝试查询以下数据集：

Customer ID     Item Purchased
1234            Bread
1235            Peanut Butter
1234            Jelly
1234            Peanut Butter
1234            Jelly
5555            Peanut Butter
5555            Peanut Butter
1235            Jelly

我正在尝试获得以下预期结果：

Customer ID     Item Purchased
5555            Peanut Butter

在这种情况下，我希望仅购买花生酱而没有其他东西的客户5555。

Answer 1

您可以使用not exists：

select t.*
from table t
where not exists (select 1 
                  from table t1 
                  where t1.Customer = t.Customer and 
                        t1.Item <> 'Peanut Butter'
                 );

您也可以使用GROUP BY子句来简化它：

select Customer 
from table t
where Item = 'Peanut Butter'
group by Customer 
having min(Item) = max(Item);

Answer 2

SELECT DISTINCT(`customer_id`) FROM `tablename` WHERE
`customer_id` IN(SELECT COUNT(DISTINCT(`items_purchased`)) AS `c`, 
`customer_id` FROM `table_name` GROUP BY `customer_id`) 
AND `items_purchased` = 'PEANUT BUTTER'

如何查询“只有”子句的字段？

2 个答案: