Peter Lalovsky

Keep it simple

Aggregate

T-SQL: Aggregate Columns (CASE or Normalization + Aggregation)

18 Dec, 2014 in T-SQL tagged Aggregate / Optimisation / SQL De/Normalization by Peter Lalovsky

In this example I will compare the execution of two possible options to aggregate multiple columns. I have data columns A, B and C and I need to show the average. “CASE” is using a formula ((A + B + C) / (1, 2 or 3)), simulating the scenarios when […]

NULL and Aggregation (AVG())

10 Dec, 2014 in T-SQL tagged Aggregate / AVG() / Goog Practice / NULL / T-SQL by Peter Lalovsky

While we create the database architecture, we decide to use the special value NULL or replace it with empty string or zero. Later on the development stage we manipulate the data and when we need to aggregate, we have to keep in mind the NULL or “blank” columns. The funny […]