SQSL logo

Over the years a the world has seen the rise of a plethora of domain specific and generalized scripting languages. Although most of them offer some sort of database engine hook, a seamless SQL integration in the host language, be it in the form of embedded SQL or sympathetic grammar, is never in the cards. With the lack of a DBA domain specific scripting language, DBAs have to put up with either using multiple tools or clumsy language and operating system interaction (or both) in order to be able to pass statements to a database engine and get rows back.

The Structured Query Scripting Language aims to bridge this gap, bringing the ability to script in a SQL manner from outside the database engine, offering seamless connection, control and formatting constructs and interaction with the operating system. With syntax features comparable to the SQL language itself, the language is designed to be obvious to anyone with SQL, PL/SQL, T-SQL, Informix SPL or 4GL expertise.

A bit of history

Back in the day, when in charge of designing and developing the ERP system at my old employer, people would often come to me and ask to implement a simple report which would consist at most of a couple of SELECT statements, minimal glue code and some formatting.
Simple task you would think, except that the publishing cycle for the application, considering the powerful technological means at our disposal (our development machine was a NCR Tower32 200 with a whooping 4M of RAM and 100MB hard disk), would be at the very least 24 hours, if not 48.
Wouldn't it be nice, I said to myself (yes, being a geek can be a very lonely affair), if I could just store the sql and formatting somewhere in the database, and have a scripting language runner do the rest of the work for me, or rather, my users?
A few late nights later a prototype implementation had been deployed, with an expansion facility and formatting capabilities. SQSL was born.

A domain specific problem example

Suppose data needs to be migrated between two different database engines, be it on a regular basis, or just as a one off. Suppose also that there is a requirement to calculate aggregates.
Several approaches spring to mind: for example unload to file from the source database engine, load from file to the target engine and finally update the data and obtain aggregates through simple SQL. Although feasible, the drawbacks of such an approach are many, and obvious.
A more effective alternative would be to write small application in java, perl or python, which selects from one source, calculates aggregates and finally inserts in the target, although the complexity of interacting with two SQL sources from your chosen host language might not make this a simple to implement or efficient proposition.

Or you could do it the SQSL way:

CONNECT TO "db1" SOURCE db2cli;
CONNECT TO "db2" SOURCE ifmx;
LET min=1000000;
LET max=0;
LET avg=0::float;
LET rows=0;
SELECT col1, col2, col3, col4
  FROM tab1
  CONNECTION "db1"
  AGGREGATE rows=rows+1, avg=avg+($1/rows)::float, ($1>max) max=$1, ($1<min) min=$1
  INSERT INTO tab1
    VALUES (?, ?, ?, ?)
    CONNECTION "db2";
DISPLAY min, max, avg, rows
  FORMAT "%08d %08d %10f %08d"
  HEADERS "min", "max", "average", "nrows";

and if you wanted to speed up things, you maybe could

CLONE 10 INTO child, pid(child);
  CONNECT TO "db1" SOURCE db2cli;
  CONNECT TO "db2" SOURCE ifmx;
  SELECT * FROM tab1
    WHERE col1>? AND col1<? USING (child-1)*100000, child*100000
    CONNECTION "db1"
    INSERT INTO tab1 VALUES (?, ?, ?, ?)
      CONNECTION "db2";
DONE;
WAIT FOR pid.* INTO r, d;
DONE;

In addition to the above, and aside from standard control and simple statements, the language sports a number of other useful features such as a simple but effective expansion facility and the ability to load dynamically data sources or user defined functions. All of them are detailed in the language reference and demonstrated in the following sample scripts.

The language is implemented in the form a of a library (two API flavours available: c or x4GL, in either Informix or Aubit flavours) which can be used to plug the interpreter in your application of choice, and a couple of sample clients, of which one has a readline library based interface and the other curses (again both Informix and Aubit 4gl based). I have also been toying with the idea of a KDE or gnome demo.

Connectivity is currently provided for Informix, DB2 and SolidDB engines, in the form of shared objects.

Further reading


Please address questions or comments to marco greco
(last updated Tue, 28 June 2009 16:50:03 GMT)