[bmf]

I'm currently reading "Mastering Relational Database Querying and Analysis" by John Carlis, which posits that SQL is inherently flawed for several reasons. To paraphrase from the text:

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.

[samuel]

I disagree with the readability part. I do heavy use of "WITH" to name my intermediate steps and comment the tricky parts (as I would do with any other programming language) and my colleagues find them pretty readable(or that's what I'm told). That's how I "reverse engineer" such monster queries, refactoring them in intermediate relations with names. Pretty often the same subselect is used more than once.

In fact, due the lack of side effects it's much easier to do than with procedural code.

[niccl]

Doh! I must be one of the SQL bunnies everyone else is superior to...

I didn't know about the WITH statement. Thanks for enlightening me.

[einhverfr]

I disagree with those criticisms of SQL, but I think it is inherently flawed from another perspective. Obviously how textbooks portray SQL has nothing to do with whether it is inherently flawed.

The real issues with SQL come down to the fact that it is an imperfect representation of relational math, and then also the dreaded ambiguity regarding NULLs.

The problem with NULLs is that NULL is used to refer to two very distinct conditions. In one case (outer joins) they are used to refer to a NULL set. In another, unknown values. These really should be distinct values.