Question

我有一个结合姓和名的SQL查询。但是如果没有名字，那么名字中就有值，那么组合的结果为空

select  CompanyContact.FirstName + ' '
 + COALESCE(CompanyContact.LastName, '')  AS Name
from bsDocument 
LEFT JOIN Contact AS CompanyContact ON CompanyContact.ContactID = bsDocument.DocumentContactID

 WHERE   bsDocument.SellerID = 3632
AND bsDocument.Module = 'bsContract'

在以下列中，CompanyContact.FirstName的值为null，而CompanyContact.LastName的值为“ Dahal”，但结果显示为null。我该如何解决？

Answer 1

在FirstName中使用COALESCE就像姓氏

select COALESCE(CompanyContact.FirstName,'') + ' '
 + COALESCE(CompanyContact.LastName, '')  AS Name
from bsDocument 
LEFT JOIN Contact AS CompanyContact ON CompanyContact.ContactID = bsDocument.DocumentContactID

 WHERE   bsDocument.SellerID = 3632
AND bsDocument.Module = 'bsContract'

Answer 2

使用concat()

select concat(CompanyContact.FirstName,' ',CompanyContact.LastName)  AS Name
from bsDocument 
LEFT JOIN Contact AS CompanyContact ON CompanyContact.ContactID = bsDocument.DocumentContactID
WHERE   bsDocument.SellerID = 3632
AND bsDocument.Module = 'bsContract'

Answer 3

您可以将stuff()与字符串串联使用：

select stuff((coalesce(' ' + c.FirstName, '') +
              coalesce(' ' + c.LastName, ''),
             ), 1, 1, '') as Name
from bsDocument d left join
     Contact c
     on c.ContactID = d.DocumentContactID
where d.SellerID = 3632 and
      d.Module = 'bsContract';

这具有很好的属性，只在名字和姓氏之间包含空格。这种结构很容易扩展为所需的任意多个可空字符串。

Answer 4

使用CASE表达式：

SELECT
CASE 
    WHEN NULLIF(CompanyContact.FirstName, '') IS NULL THEN CompanyContact.LastName
    ELSE CompanyContact.FirstName + ' ' + CompanyContact.LastName
    END AS Name
FROM bsDocument 
LEFT JOIN Contact AS CompanyContact ON CompanyContact.ContactID = bsDocument.DocumentContactID
WHERE bsDocument.SellerID = 3632
AND bsDocument.Module = 'bsContract'

如果第一个值为null，则在合并两个值时如何获取最后一个值？

4 个答案: