Now it became time to conveert some SQL statements. Even though many SELECT SQL statements will run unchanged in MYSQL it might be wise to check and see if they are performing well. There are some differences in how VFP and MYSQL optimize queries and a query that just performs great in VFP might be very slow in MYSQL. And then there are some cases where we have to replace things that are possible in VFP but not supported in MYSQL.
First lets assume that our tables all have lots of records. After all it does not pay to spend time on optimizing on tables with a few dozend records. I also will not go into VFP optimization here as this is a MYSQL blog.
Lets assume for our first case we might have a table with invoice detail records and a table with items that are on sale. So now we want to get maybe 2 queries. One to show a total of all the items that were on sale and the second a total of all the items not on sale. I will leave …[Read more]