Data Engineering Technical Blog

What is running sum ? Running sum is basically sum of all previous rows till current row for a given column. The rows can be ordered/indexed on certain condition while collecting the sum.  Below is the example where we collect running sum based on transaction time (datetime field)  On Running_Sum column you can notice that its sum of all rows for every row. How can you obtain running sum in SQL ? Using SQL windowing function  We will create a table with transaction data as shown above and try to obtain running sum.  Syntax for running total   SUM(<COLUMN>) OVER (PARTITION BY <COLUMN(S)> ORDER BY <COLUMN(S)) Since in our example we don't have any group to get running total so we will not use PARTITION BY.  Lets jump into example  We have created a table variable and added values and we are ready with data to be validated. Below you can copy the code for above example.  DECLARE @Running_Total_Example TABLE ( transaction_date DATE...