How can I speed up mysql query when using running a select using a count(distinct ) query?

Try this using a JOIN instead of a subquery.

A guess since we don't know any indexes. But a very common mistake is too not have an index covering al the tables in the where clause. Example from your outer select.

I cant really gove you an answer,but what I can give you is a way to a solution, that is you have to find the anglde that you relate to or peaks your interest. A good paper is one that people get drawn into because it reaches them ln some way.As for me WW11 to me, I think of the holocaust and the effect it had on the survivors, their families and those who stood by and did nothing until it was too late.