Re: Storing query language in relations

pbrazier_at_cosmos-uk.co.uk (Paul) wrote in message news:<51d64140.0209230146.320e13b2_at_posting.google.com>...

> If we accept that a relational database is the
> most logical way to
> hold structured data, why not go a step further
> and store the actual
> queries in relational format?

What is "unstructured" data anyway?! :-)

> ...why not go a step further and store the actual
> queries in relational format?

Sure... but there is no reason you couldn't do a whole imperative language including queries (expressions). It would only be a matter of having a table for each language element. Something like this:

create table InsertStatement
{
  Statement_ID : StatementID,
  SourceExpression : ExpressionID,
  TargetExpression : ExpressionID,
  key { Statement_ID },
  ...
};

create table Expression
{
  ID : ExpressionID,
  ResultType : TypeID,
  ExpressionType : ExpressionType,
  key { ID }
};

create table UnaryOperatorExpression
{
  Expression_ID : ExpressionID,
  Operand : ExpressionID,
  key { Expression_ID },
  ...
};

create table IntegerLiteralExpression
{
  Expression_ID : ExpressionID,
  Value : Integer,
  key { Expression_ID },
  ...
};

Of course you would want to build some supporting operators:

create operator EvaluateExpression(AExpressionID : ExpressionID) : Generic
...

What would also be an interesting exercise would be to model a word processor! So much for "unstructured" data!

--
Nathan Allan