我有一个应用程序，它将与服务器同步，并每天更新数据。在同步期间，我删除了某些实体的所有数据，并重新加载了新数据。我正在使用以下代码：
func SyncronizeUserComments(theData : [[AnyHashable : Any]])
{
// Delete User Comments for this User and Connection
let commentRequest : NSFetchRequest<NSFetchRequestResult> = PT_UserComments.fetchRequest()
commentRequest.predicate = NSPredicate(format: "connection = %@ AND user == %@", Global_CurrentConnection!, Global_CurrentUser!)
coreData.processDeleteRequest(request: commentRequest)
// ADD the Comments to CoreData
for index in 0..<theData.count {
let result : [AnyHashable : Any] = theData[index]
if let commentID = result["Comment_ID"] as? String, let commentText = result["Comment_Text"] as? String, let commentTitle = result["Comment_Title"] as? String
{
let newUserComment = PT_UserComments(context: …我在带有日期戳的表中记录了用户操作.
每次用户进入项目时,都会记录他们查看该项目并标记日期时间.
我想获得用户最后进入的TOP 20项目.
这是我到目前为止:
SELECT DISTINCT TOP (20) Users_Tran_ID
FROM App_UserLog
WHERE (Users_ID = 'ADMIN') AND (Users_Transaction LIKE 'Permit Viewed%')
ORDER BY App_UserLog.Users_LogDate DESC
问题是,我不想在输出中使用Users_LogDate,因为我需要UNIQUE Users_Tran_ID.
当我从SELECT中删除Users_LogDate时,我收到以下错误:
ORDER BY items must appear in the select list if SELECT DISTINCT is specified.
这是我得到的基本选择和结果集.我只想要不同的Users_Tran_ID,只需要TOP 20.
ADMIN Permit Viewed B2011-0012 2013-08-29 17:35:04.000
ADMIN Permit Viewed B2011-0012 2013-08-29 17:29:09.000
ADMIN Permit Viewed B2006-0043 2013-08-29 17:29:05.000
ADMIN Permit Viewed B2011-0012 2013-08-29 17:28:49.000
ADMIN Permit Viewed B2008-0167 2013-08-29 17:17:13.000
ADMIN Permit Viewed B2006-0043 2013-08-29 17:17:08.000 …