Before PostgreSQL, Bruce Momjian wrote an SQL in Shell
Bruce Momjian is best known as a member of the PostgreSQL core team, what most people don't know is that in the early '90s, before he was working on Postgres, he wrote another SQL database.
And he wrote it in shell.
The result, SHQL is a pretty damn cool piece of software. I had an informal chat about it with Bruce a couple weeks ago at SCALE, and just had to write about it. The source is definitely a fun browse because not only is it a cool idea, it's the kind of software that belongs to a specific time. Asking Bruce how he picked shell, he mentioned that it was a language he knew, and that Perl just seemed like it was too heavy at the time.
What's immediately striking about SHQL is its completeness given its mere 760 SLOC. It supports, CREATE, DELETE, DROP, INSERT, SELECT, UPDATE, WHERE, PRINT, EDIT as commands, but has surprising completeness, including UNION and DISTINCT. It even supports a rudimentary form of views, through which you can do a basic sort of joining!
SHQL is not pure shell, it makes heavy use of both awk and grep. For instance, updating a table involves filtering the entire table through awk, directing the output to a tmp file, then replacing the current data file with the new one.
One install note, on my ubuntu system /bin/sh has a few issues with it, I'd definitely use bash proper to run it. Also, be sure to mkdir -p ~/shql/MYDBNAME.
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