MySQL SQL Execution steps

The basic steps are 1.from 2.join on 3.where 4.group by 5.having 6.order by 7.select 8.distinct, Sum,... 9.limit Join table must have an index or the Cartesian product. Inner join is especially correct in that MySQL will first select the best table join table method with the filter condition of base on where. Then it is the for 1st table that will filter the where to start the join. But we usually use straight join to control it, lest we don't know that the table is going to be a join in the end. Having is filtering out the rows after group by, this time the filter can use the count sum of those, which is not used in the where.

MySQL SQL Execution steps