158 karma · joined March 5, 2009
http://www.nhplace.com/kent/Papers/Technical-Issues.html
What I took away from it was that macros get more tricky to write when you have possible variable capture for functions, which we humans seem to be a little more blind to than for values.
Item 18 contains the compatibility concerns for existing code, which the guys writing the standard seemed to think critical to keep the various vendors on board.
First, both the syntax and the way querying is generally presented in textbooks, lead you to think that your task when querying is to display one unnamed table. The author objects to each of those four words.
Second, many people have found querying with SQL terribly difficult. Even experts find SQL hard to create and read. Do not be surprised if an analyst struggles to understand his/her own SQL. It is impossible for users to understand any but the simplest SQL.
Third, SQL practice suffers from the notion of a "correlated query" -- which has a monolithic subquery that is executed repeatedly via looping, once for each value of a candidate row picked by an outside SELECT.
The book has much more to say on the topic of SQL before going on offer relational algebra (built on top of SQL) as a n alternative.