如果行存在或不存在，則顯示布爾

Question

我有表[合同]與列[id]，[number]。我還有一些字符串格式的數字：'12342'，'23252'，'1256532'。我想要得到這樣的輸出。

1535325 | no 
12342 | yes 
23252 | yes 
434574 | no 
1256532 | yes 

我當然可以這樣寫，讓我有行，但我怎麼能確定該行不存在，並得到上面的輸出：

SELECT [Id] 
     ,[Number] 
    FROM [Contracts] 
    where [Number] in 
    ('12342', '23252', '1256532') 

Answer 1

你可以把值代入臨時表或表變量和做left join：

declare @d table (Number varchar(10)) 
insert into @d values ('12342'), ('23252'), ('1256532'), ('xxxx') -- last one is not in Contracts 

SELECT c.[Id], c.[Number], case when d.Number is NULL then 'no' else 'yes' end [This Number from C is in D also] 
FROM [Contracts] c 
    left join @d d on d.Number = c.Number 

爲 「相反」 使用right join

SELECT c.[Id], d.[Number], case when c.Number is NULL then 'no' else 'yes' end [This Number from D is in C also] 
FROM [Contracts] c 
    right join @d d on d.Number = c.Number