Advanced querying techniques

BigQuery offers various advanced querying techniques that allow users to perform complex analyses and extract valuable insights from their datasets. These techniques leverage advanced SQL functionalities and BigQuery-specific features to handle challenging querying scenarios.

Subqueries

Subqueries allow you to nest one query inside another, enabling you to break down complex problems into smaller more manageable parts. You can use subqueries in various ways, such as performing calculations based on the results of a subquery, filtering data, or creating temporary tables for further analysis. In the following example, which was performed on the Google Trends dataset, an aggregate subquery calculates the average rank of a search term in the top_terms table in the Charlotte NC designated market area (DMA):

SELECT DISTINCT(term), rank, refresh_date,
  (SELECT AVG(rank) FROM `bigquery-public-data.google_trends.top_terms` WHERE refresh_date...