Algorithm for neatly indenting SQL statements (Python implementation would be nice)

Question

I'd like to reformat some SQL statements that are a single string with newlines in to something that's much easier to read.

I don't personally know of a good coding style for indenting SQL - how should nested queries / where clauses / left joins / etc by represented to maximise readability?

Has anyone seen a pretty-printing algorithm that does this already? In Python would be even better.

Answer 1

I personally use SQL Inform for quick SQL formating, which is written in Java and is unfortunately not open source, so there is no access to the underlying algorithm.

Answer 2

Perhaps part of the difficulty in finding a tool is that there are so many different "standard" SQL formatting conventions. Here are two SO questions that describe people's preferences:

• http://stackoverflow.com/questions/519876/sql-formatting-standards
• http://stackoverflow.com/questions/522356/what-sql-coding-standard-do-you-follow

Answer 3

Don't know if it answers your question, but I generally use this strategy

SELECT what1, what2, etc,
FROM table
WHERE condition
  AND condition
  AND condition
ORDER BY whatever

But that's just me. I don't think proper automatic tools exist.

Answer 4

You can try sqlparse. It's a Python module that provides simple SQL formatting. A online demo is available here.