According to stackoverflow user CodesInChaos “ticks are simply the smallest power-of-ten that doesn’t cause an Int64 to overflow when representing the year 9999”.
This is clearly not right; it seems SQL Server has guessed that the variable would match 50% of the rows in the table. A .Net tick is a duration of time lasting 0.1 microseconds. SQL Server DATEDIFF function returns the difference in seconds, minutes, hours, days, weeks, months, quarters and years between 2 datetime values. SQL date format functions like the DateDiff SQL function and DateAdd SQL Function are oft used by DBAs but many of us never took the time to fully understand these extremely useful features. Each one performs a different task. This article focuses on developing a basic understanding of how to use one of the most common Transact-SQL date functions: DATEADD, DATEDIFF, and DATEPART. Let’s talk about the DATEDIFF vs. DATEADD functions in SQL Server. sql server datediff函数引发的性能问题 今天，一哥们反馈系统很慢，很卡，让我远程看一下。 我远程过去查了一下数据库系统，发现很多阻塞，语句都基本相似，并且表的数据也不大，只有10多万条记录。 For professionals just getting started with SQL Server, these functions are … La fonction doit respecter la syntaxe suivante : SELECT DATEDIFF( type_limite, date1, date2 ); Le paramètre “type_limite” permet de spécifier si le résultat doit être exprimé en jour, semaine, mois, année …
SQL Server.
Quick Example: -- The difference is days between today and yesterday SELECT DATEDIFF(dd, GETDATE() - 1, GETDATE()); -- Returns: 1 -- The number of seconds in 24 hours SELECT DATEDIFF(ss, GETDATE() - 1, GETDATE()); -- Returns: 86400 Yay!
You need to put the where clause last SELECT ProposalDate, DateDiff("wk", ProposalDate, getDate()) AS [Open Weeks] FROM proposals WHERE DateDiff("wk", ProposalDate, getDate()) = 2 Keep in mind that this query will be a table or index scan because you are using a function in the where clause. The first two queries are fixed (by changes to the cardinality estimator or other fixes), meaning that the DATEDIFF arguments are no longer switched.
Sous SQL Server, la donction DATEDIFF s’utilise un peu différemment. When you look at the Tick property of DateTime, you’ll see that it represents the number of ticks since January 1st 0001. I found a slightly different issue in SQL Server 2014. select datediff(day, 7, '1900-01-08') If what you said were true, it would substitute the default date and time for the 7 and produce a result of 7, whereas the actual result is 0. SQL Server 2014. But why 0.1 microseconds?