The querying half of BigQuery on one page, every line explained: aggregates and joins, CTEs, subqueries, EXISTS, semi-joins and anti-joins, window functions, UNNEST, user-defined functions and materialized views.
Most BigQuery mistakes are not syntax errors. They are a COUNT(*) that quietly counts the NULLs a LEFT JOIN invented, a NOT IN that returns nothing because one value was NULL, or a correlated subquery that runs once per row when a window function would have done it in a single pass. This sheet puts twelve topics side by side, each with the handful of lines that matter and a plain explanation of what every one of them does, so the traps are visible next to the syntax rather than discovered in a bill. Keep it open while you query, or save the image and pin it nearby.
It runs from aggregates and joins through CTEs and every flavour of subquery, on to EXISTS, anti-joins, window functions and running totals, and finishes with the BigQuery-specific parts: flattening nested data with UNNEST, writing your own functions, and letting materialized views do the repeated work for you.
Hope this helps.
