Lag based on Month
Our goal is to create a 1 month lag column (rather than by row). The LAG(M/Y) column output of 01/2000 should line up with 02/2000 in the M/Y column, etc. Attached is a tiny subset example of water use by m/y; whereas, our full table contains more than 59 million rows. The full table consists of water use for more than 430,000 customers for each each month over many years. We're open to all s...