sql - sql server查询：如何选择超过1个订单的客户

Question

我是一个 sql server 新手，并试图选择所有具有超过 1 个 orderid 的客户。该表如下所示：

CREATE TABLE [dbo].[orders](
    [customerid] [int] NULL,
    [orderid] [int] NULL
) ON [PRIMARY]
GO
INSERT [dbo].[orders] ([customerid], [orderid]) VALUES (1, 2)
INSERT [dbo].[orders] ([customerid], [orderid]) VALUES (1, 3)
INSERT [dbo].[orders] ([customerid], [orderid]) VALUES (2, 4)
INSERT [dbo].[orders] ([customerid], [orderid]) VALUES (2, 5)
INSERT [dbo].[orders] ([customerid], [orderid]) VALUES (3, 1)

Answer 1

select  customerid
,       count(*) as order_count
from    orders
group by
        customerid
having  count(*) > 1

Answer 2

由于您可能在某些时候需要客户数据，因此您也可以尝试：

select *
from customers
where exists (
    select count(*)
    from    orders
    where customers.id = customerid
    group by customerid
    having  count(*) > 1
)