T-SQL applies self-join row-by-line statistics sum value

The main method is to use the aggregation function to realize the sum value of a column by row by self-join.

This is before the statistics

After the statistics, the result is

The implementation code is as follows:

1 Create TableSales2 ( 3ProductNamenvarchar( -) 4, Dateofmonthnvarchar( -)5, quantityint 6 )7 8 Insert  intoSales9 Select 'P1','201401', -Ten Union  All  One Select 'P1','201402', - A Union  All  - Select 'P1','201403', - - Union  All  the Select 'P2','201401', $ - Union  All  - Select 'P2','201402', - - Union  All  + Select 'P2','201403', - - Union  All  + Select 'P2','201401', - A Union  All  at Select 'P3','201402', - - Union  All  - Select 'P3','201403', - -  - --SELECT * FROM Sales -  in SelectRow_number () Over(Order  byproductname,dateofmonth,quantity) SID,* -  into#Temp to  fromSales +  - --SELECT * from #temp the SelectDense_rank () Over(Order  byProductName) RID,* *  into#temp1 $  from#TempPanax Notoginseng  - Select the A.productname + , A.dateofmonth A , A.quantity the,sum(b.quantity) as Total +  from#temp1 A, #temp1 b - whereA.sid>=B.sid andA.rid=B.rid $ Group  byA.productname,a.dateofmonth,a.quantity

T-SQL applies self-join row-by-line statistics sum value