Sql r'我建议只需添加一个计数列，您就可以知道它是否存在。@Tony\u Henrich。我不知道你想要什么样的结果集。如前所述，您将为数据中的每个订单（或至少每个电视订单）获得一个单独的行。不过，描述表明您希望每个客户有一行。但是如果是这样，为什么要在选择中

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r'我建议只需添加一个计数列，您就可以知道它是否存在。@Tony\u Henrich。我不知道你想要什么样的结果集。如前所述，您将为数据中的每个订单（或至少每个电视订单）获得一个单独的行。不过，描述表明您希望每个客户有一行。但是如果是这样，为什么要在

选择中包含订单信息呢？@GordonLinoff我添加了订单信息，所以显示了信息，但是是的，订单不在选择中。我希望返回一行如果一个客户有10个订单会发生什么？哦，它将为一个客户返回多行。修改了我要查询的问题，需要在单个案例声明中处理。不是多行。我已尝试在单个case语句中处理。让我知道这是否对你有帮助这并不能以任何形式回答我的问题。这个问题是关于使用case语句并根据当前数据类型显示特定文本的特定问题。@Tony\u Henrich我添加了case语句。这会产生一个错误：“Customer.CustId”列在选择列表中无效，因为它既不包含在聚合函数中，也不包含在GROUP BY子句中。@Tony\u Henrich。我推荐了聚合，然后没有包括
分组依据
。已经修好了。
CREATE TABLE [dbo].[Customer](
    [CustId] [int] NOT NULL,
    [CustomerName] [varchar](50) NOT NULL
)

CREATE TABLE [dbo].[Order](
    [OrderId] [int] NOT NULL,
    [CustId] [int] NOT NULL,
    [Description] [varchar](50) NOT NULL
)



INSERT INTO customer (CustId, CustomerName) VALUES
(1, 'John'),
(2, 'Tom')
GO

INSERT INTO [order] (OrderId, CustId, Description) VALUES
(1, 2, 'TV')
go

IF OBJECT_ID('tempdb..#temp') IS NOT NULL
    DROP TABLE #temp;

SELECT

    'TV' Description INTO #temp

SELECT c.CustId
    ,t.Description
   ,o.Description
   ,CASE
        WHEN t.Description IS NULL THEN 'Did not find any orders'
        WHEN t.Description IS NULL THEN 'Found order but not TV order'
        ELSE 'Found TV Order' 
    END Status

FROM Customer c
LEFT JOIN [Order] o
    ON o.CustId = c.CustId
LEFT JOIN #temp t
    ON t.Description = o.Description
WHERE c.CustId = 1

 select a.custid,a.CustomerName,orderid=isnull(b.orderId,0),
     description=iif(b.description is null,'Did not Find Any Order',b.description) 
     from Customer a left join [Order] b on a.custid=b.Custid

,case when  t.Description = o.Description  then 'Found TV Order'
         when  isnull(t.Description,'No') = isnull(o.Description,'No') then 'Did not find any orders'
         when  isnull(t.Description,'No') <> isnull(o.Description,'No') then 'Found order but not TV order'
   end Status

SELECT c.CustId
    ,t.Description tdesc
   ,o.Description odesc

   ,case when  t.Description = o.Description  then 'Found TV Order'
         when  isnull(t.Description,'No') = isnull(o.Description,'No') then 'Did not find any orders'
         when  isnull(t.Description,'No') <> isnull(o.Description,'No') then 'Found order but not TV order'
   end Status
  /*  ,CASE
        WHEN t.Description IS NULL THEN 'Did not find any orders'
        WHEN t.Description IS NULL THEN 'Found order but not TV order'
        ELSE 'Found TV Order' 
    END Status  */

FROM Customer c
LEFT JOIN [Order] o ON o.CustId = c.CustId
LEFT JOIN #temp t   ON t.Description = o.Description

 select CustId,descpt 
    from 
    (
    SELECT c.CustId
        , case when o.Description is null then 'Did not find any orders' end   descpt 
    FROM Customer c
    LEFT JOIN [Order] o ON o.CustId = c.CustId  ) no_orders
    where no_orders.descpt is not null

    union 
    select CustId,descpt 
    from 
    (
    SELECT c.CustId
        , case when o.Description ='TV' then 'Found order for TV ' end   descpt 
    FROM Customer c
    LEFT JOIN [Order] o ON o.CustId = c.CustId  ) no_orders
    where no_orders.descpt is not null

    union
    select CustId,descpt 
    from 
    (
    SELECT c.CustId
        , case when o.Description <> 'TV' then 'Found order but not TV order' end   descpt 
    FROM Customer c
    LEFT JOIN [Order] o ON o.CustId = c.CustId  ) no_orders
    where no_orders.descpt is not null

select
    c.CustId,
    t.Description,
    case
        when o.Description is null then
            'Did not find any orders'
        when o.Description <> t.Description then
            concat('Found order but not ',t.Description,' order')
        else
            concat('Found ',t.Description,' order')
    end as status
from dbo.Customer as c
    cross join (
        select 'TV' as Description
    ) as t
    outer apply (
        select top 1 tt.Description
        from dbo.[Order] as tt
        where
            tt.CustId = c.CustId
        order by
            case when tt.Description = t.Description then 0 else 1 end
    ) as o

select
    c.CustId,
    t.Description,
    case
        when o1.Description is not null then
            concat('Found ',t.Description,' order')
        when o2.OrderId is not null then
            concat('Found order but not ',t.Description,' order')
        else
            'Did not find any orders'
    end as status
from dbo.Customer as c
    cross join (
        select 'TV' as Description
    ) as t
    left join dbo.[Order] as o1 on
        o1.CustId = c.CustId and
        o1.Description = t.Description
    outer apply (
        select top 1 tt.OrderId
        from dbo.[Order] as tt
        where
            tt.CustId = c.CustId and
            tt.Description <> t.Description
    ) as o2

CREATE TABLE [dbo].[Customer](
    [CustId] [int] NOT NULL,
    [CustomerName] [varchar](50) NOT NULL
)
CREATE TABLE [dbo].[Order](
    [OrderId] [int] NOT NULL,
    [CustId] [int] NOT NULL,
    [Description] [varchar](50) NOT NULL
)
CREATE TABLE [dbo].[FakeTemp](
    [Description] [varchar](50) NOT NULL
)
INSERT INTO FakeTemp (Description) VALUES
('TV')
GO
INSERT INTO customer (CustId, CustomerName) VALUES
(1, 'John'),
(2, 'Tom'),
(3, 'Steve')
GO
INSERT INTO [order] (OrderId, CustId, Description) VALUES
(1, 1, 'TV')
go
INSERT INTO [order] (OrderId, CustId, Description) VALUES
(2, 2, 'VCR')
go
INSERT INTO [order] (OrderId, CustId, Description) VALUES
(3, 1, 'VCR')
go


select c.CustomerName, count(OrderId) as TV_Orders
, (select count(OrderID) from [order] where CustId = 1) as All_Orders
from customer c
left outer join [order] o on c.CustId = o.CustId
inner join FakeTemp t on o.Description = t.Description
where c.CustID = 1
group by c.CustomerName, t.Description

select
  CASE
      WHEN (select count(OrderID) from orders where CustId = 1) = 0 THEN 'Did not find any orders'
      WHEN count(OrderID) = 0 THEN 'Found order but not TV order'
      ELSE 'Found TV Order'
  End as Status

from customer c
left outer join [orders] o on c.CustId = o.CustId
inner join FakeTemp t on o.Description = t.Description
where c.CustID = 1
group by c.CustomerName, t.Description

SELECT c.CustId,
       (CASE WHEN COUNT(o.CustId) = 0
             THEN 'Did not find any orders'
             WHEN SUM(CASE WHEN o.Description = 'TV' THEN 1 ELSE 0 END) = 0
            THEN 'Found order but not TV order'
            ELSE 'Found TV Order' 
       END) as Status
FROM Customer c LEFT JOIN 
     [Order] o
     ON o.CustId = c.CustId
WHERE c.CustId = 1
GROUP BY c.CustId;