DATEDIFF子查询在mysql中返回超过1行

使用DATEDIFF查询的特定部分存在问题：

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我见过一些人提到在子查询中使用IN而不是=，但我似乎无法让它工作。有什么想法吗？提前感谢。

我可以通过在已识别状态后添加“限制1”来实现查询：

从ApplicationStatusChangeLog a中选择CreatedOn，其中a.ApplicationId=b.ApplicationId

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并且a.status='Approved'限制1，从ApplicationStatusChangeLog a中选择CreatedOn，其中a.ApplicationId=b.ApplicationId和a.status='Pending Approval'限制1

请显示整个查询。我的猜测是，这种选择中的选择并不是最好的方法。经过编辑以包含整个查询-再次感谢您的帮助。对有问题的描述不算多。请至少在这里提供一个人们可以回答的问题。例如，示例数据、您期望的输出以及您正在获得的输出将大大有助于让SQL墙变得易懂。

select 1 as NumApps, 
LenderInfo.Name as LenderName,
CASE WHEN ApplicationInfo.AEType IS NULL OR ApplicationInfo.AEType = 0 THEN 'Unknown' ELSECONCAT    (AEContact.FirstName, ' ', AEContact.LastName) END As AEName,
CASE WHEN b.createdby > 0 THEN CONCAT (contactinfo.firstname, ' ', contactinfo.lastname) END AS LogActionBy,
CASE WHEN ApplicationInfo.RecertificationById IS NULL THEN CASE WHEN ApplicationInfo.IsCorrespondent IS NULL OR ApplicationInfo.IsCorrespondent = 0 THEN 'Wholesale' ELSE 'Correspondent' END ELSE CASE WHEN ApplicationInfo.IsCorrespondent IS NULL OR ApplicationInfo.IsCorrespondent = 0 THEN 'Wholesale - Recert' ELSE 'Correspondent- Recert' END END As AppType,
Applicationinfo.SubmissionDate,
ApplicationInfo.ApplicationID,
b.status AS LogStatus,
b.CreatedOn as LogDate,
companyinfo.Name,
companyinfo.NMLSEntityID,
applicationinfo.CreatedDate,        
ApplicationInfo.Status as ApplicationStatus,
ApplicationInfo.StatusChangeDate,
DATEDIFF ((Select CreatedOn From ApplicationStatusChangeLog a where a.ApplicationId = b.ApplicationId
And a.status = 'Approved'),(Select CreatedOn From ApplicationStatusChangeLog a Where a.ApplicationId = b.ApplicationId And a.status = 'Pending Approval')) AS DaysToApprove
from applicationinfo 
INNER JOIN CompanyInfo ON(ApplicationInfo.CompanyId = CompanyInfo.CompanyId)
left join   CompanyInfo As LenderInfo ON (ApplicationInfo.LenderId = LenderInfo.CompanyId)
LEFT JOIN UserInfo ON (UserInfo.UserId = ApplicationInfo.LastModifiedById)
LEFT JOIN ContactInfo ON UserInfo.ContactId = ContactInfo.ContactId
LEFT JOIN ContactInfo AS Comergence ON(ApplicationInfo.ComergenceRepId = Comergence.ContactId)
LEFT JOIN UserInfo AS AEUser ON(AEUser.UserId = ApplicationInfo.AEType)
left join   paymentinfo on applicationinfo.applicationid = paymentinfo.applicationid
Inner join applicationstatuschangelog b on applicationinfo.applicationid = b.applicationid
LEFT JOIN ContactInfo AS AEContact ON(AEContact.ContactId = AEUser.ContactId)
LEFT JOIN UserInfo AS StatusUser ON(StatusUser.UserId = ApplicationInfo.StatusChangeById)
LEFT JOIN ContactInfo AS StatusContact ON(StatusContact.ContactId = StatusUser.ContactId)
LEFT JOIN ApprovalStatus ON(ApplicationInfo.ApplicationId = ApprovalStatus.ApplicationId AND ApplicationInfo.CompanyId = ApprovalStatus.CompanyHQId
AND ApplicationInfo.CompanyId = ApprovalStatus.CompanyId)
Where ApplicationInfo.Status NOT In ('Approved Monitor Only')
AND LenderInfo.ActiveLenderContract = 1
AND COALESCE(ApplicationInfo.IsDeleted,0) <> 1
AND b.Status NOT IN ('Incomplete', 'Not Submitted')
Group BY b.ApplicationID`