Are JOIN queries faster than several queries? (You run your main query, and then you run many other SELECTs based on the results from your main query) I’m asking because JOINing them would complicate A LOT the design of my application If they are faster, can anyone approximate very roughly by how much? If it’s … Read more
I’ve been using indexes on my MySQL databases for a while now but never properly learnt about them. Generally I put an index on any fields that I will be searching or selecting using a WHERE clause but sometimes it doesn’t seem so black and white. What are the best practices for MySQL indexes? Example … Read more
While reading some SQL Tuning-related documentation, I found this: SELECT COUNT(*) : Counts the number of rows. Often is improperly used to verify the existence of a record. Is SELECT COUNT(*) really that bad? What’s the proper way to verify the existence of a record? 9 Answers 9
Is there a better way of doing a query like this: SELECT COUNT(*) FROM (SELECT DISTINCT DocumentId, DocumentSessionId FROM DocumentOutputItems) AS internalQuery I need to count the number of distinct items from this table but the distinct is over two columns. My query works fine but I was wondering if I can get the final … Read more
