Nobody warns you about this part. You learn joins, you learn aggregation, you land a job, and then you discover that the field called district contains “Pune”, “pune”, ” Pune “, “PUNE”, “Pune ” and “Punr”. And a number. And, for reasons nobody can explain, the word “test”. Cleaning data is the majority of analytics … Read more
There is a specific kind of silence that happens when you run a query in front of someone. The spinner turns. You start talking to fill the gap. You mention that the table is quite large. Two minutes later you are apologising. Most slow queries are not slow because the database is weak or because … Read more
There is a moment in most analysts’ careers where they stop writing SQL that works and start writing SQL that is good. For a lot of people, that moment is window functions. Before you learn them, certain problems feel genuinely impossible in SQL. Rank each salesperson within their region. Show each month alongside the previous … Read more
There is a specific kind of Monday morning misery familiar to anyone who has worked in analytics. Open the laptop, run four queries, paste the results into a spreadsheet, fix the formatting because the date column came through as text again, write a short email, attach the file, send. Forty minutes. Every week. Forever. The … Read more