首先得知道,lead和lag是使用over处理后的结果集来取值的,over内部先根据partition分区(如果没有显示指定partition,则整个结果集为一个区),分好区后根据order by指定的排列顺序对分区完成的临时结果集进行排序,然后从1开始为排好序的每1行递增分配序号生成新的临时结果集B,lead(lag)就使用有序号的临时结果集B取后(...
LEAD函数 LEAD函数与LAG函数刚刚相反,它是向前偏移指定的行数,默认是1行。 语法哈参数与LAG类似,这里就不重复介绍了。我们直接看示例: SELECT ID,NUM, LEAD(NUM) OVER (PARTITION BY ID ORDER BY NUM) AS OneArgs, LEAD(NUM,1) OVER (PARTITION BY ID ORDER BY NUM) AS TowArgs, LEAD(NUM,2,0) OVER...
Lag(exp_str,offset,defval) over() Lead(exp_str,offset,defval) over() --exp_str...
LEAD(b.OperatorTime,1, b.OperatorTime)OVER( PARTITIONBYb.NoORDERBYb.OperatorTime )ASNextTimeFROMTest b ) aWHEREDATEDIFF(HH, a.BeforTime, a.OperatorTime)<24ANDDATEDIFF(HH, a.OperatorTime, a.NextTime)<24ANDa.NoIN(SELECTc.NoFROMdbo.Test cGROUPBYc.NoHAVINGCOUNT(c.No)>1) LAG函数: 作用:...
-- lead和lag函数示例 select Id ,LEAD(Name,1) over(order by Id) 'nextName_IdAsc' ,LEAD(Name,1) over(order by Id desc) 'nextName_IdDesc' ,LEAD(Name,1) over(partition by Age order by Id desc) 'nextName_PAge_IdDesc' ,LAG(Name,1) over(order by Id) 'preName_IdAsc' ...
跨组/密集等级的SQL Server Lag / Lead是一种在SQL Server数据库中用于计算行之间差异的函数。它们通常用于分析和处理时间序列数据或需要比较相邻行的数据。 Lag函数用于获取当前行之前的指定行数的数据,而Lead函数用于获取当前行之后的指定行数的数据。这两个函数可以帮助我们在查询结果中访问其他行的数据,从而实现...
This is where the LAG & LEAD functions step in To go back a record, we call the LAG function. Within the LAG function, we must define the field that we want to pull in (order date) and how many records back do you want to go (1). Next we want to group by (partition by) and...
SQL Server Denali CTP3 finally gives us LAG and LEAD. Here is the description directly stolen from BOL:Accesses data from a previous row in the same result set without the use of a self-join in Microsoft SQL ServerCode-Named “Denali”, Community Technology Preview 3 (CTP 3)...
下面SQL语句使用了LEAD和LAG函数: SELECT [id],[title], LAG([id]) OVER (ORDER BY [id]) AS [前一篇主键], LEAD ([id]) OVER (ORDER BY [id]) AS [后一篇主键] FROM [#tsource]
Lag函数类似于Lead函数,只是Lead函数看起来与Lag函数相反。 也就是说,Lag(n)等效于Lead(-n)。 示例 下例将返回 2001 年 12 月的值: SELECT [Date].[Fiscal].[Month].[February 2002].Lag(2) ON 0 FROM [Adventure Works] 下例将返回 2002 年 3 月的值: ...