¿Cuál es un uso principal de la función UNION ALL (fusionar todo) en las consultas de AMC?

The UNION ALL operator in AMC SQL queries is primarily used to combine the result sets of two or more SELECT statements into a single result set. This is particularly useful for unifying events from different tables, such as combining impression data from one table with click data from another, or merging data from various campaign tables into a single view for analysis. It includes duplicate rows, which is often desired when analyzing event streams. Grouping records based on a specified field is achieved using the GROUP BY clause, not UNION ALL. Summarizing key fields in event tables is typically done with aggregate functions like SUM, COUNT, AVG, etc., often in conjunction with GROUP BY, not UNION ALL.