4 ms·

It's not a matter of aesthetics; it's a matter of power. If each table transformation is a function, the language becomes considerably more flexible. Consider t

It's not a matter of aesthetics; it's a matter of power. If each table transformation is a function, the language becomes considerably more flexible. Consider the following syntax: users where(u => u.login = "foo" and u.passwd = SHA1("secret" + u.salt)) Since "where" is a function, we can isolate just this transformation: authenticate(login, password) := where(u => u.login = login and u.passwd = SHA1(password + u.salt)) Now "authenticate" is a table transformation as well: users authenticate("foo", "secret") This is a trivial example, but this could just as easily apply to more complex queries. One could construct functions to manage "nested set" tables, or create custom aggregation functions. Everything that is currently difficult or impossible under SQL. Because SQL is so limited in what you can abstract, there's very little room to factor out common code. Views, stored procedures and even T-SQL functions just operator on set tables. With a more flexible syntax, one could have third-party libraries containing more complex table transformations. Personally, I wonder whether we need a separate language for database queries at all. It would be nice if there were a just a library we could use to create our own database server inline, using whatever language we wish.

DenisM 17y ago
I see what you mean, and yes it would be nice. In essence what you advocate is a table type and a number of tables conforming to that type could be then passed into a function which operates over the parameter given what it knows about it by the type description. It's a very appealing idea and many times I wished it was possible. My guess as to why it isn't possible is that in the database world there is an assumption that all records of the same type lie in one table, i.e. the table is the type. And if you look at it form theoretical relational theory point of view, that is so. Alas in practice we do have things like third-party components and we have to worry about lifetime (e.g. transient table-typed variables). To be fair Oracle I think has something called "package" which allows writing reusable code. Don't know much about it, but supposedly that's what it does. Also, MSSQL has notion of Table Type which can be used to declare variables. I actually implemented (a part of) it while I worked there. :)

DenisM 17y ago

I see what you mean, and yes it would be nice. In essence what you advocate is a table type and a number of tables conforming to that type could be then passed into a function which operates over the parameter given what it knows about it by the type description. It's a very appealing idea and many times I wished it was possible. My guess as to why it isn't possible is that in the database world there is an assumption that all records of the same type lie in one table, i.e. the table is the type. And if you look at it form theoretical relational theory point of view, that is so. Alas in practice we do have things like third-party components and we have to worry about lifetime (e.g. transient table-typed variables). To be fair Oracle I think has something called "package" which allows writing reusable code. Don't know much about it, but supposedly that's what it does. Also, MSSQL has notion of Table Type which can be used to declare variables. I actually implemented (a part of) it while I worked there. :)