[std.database] at compile time

[foobar]

Andrei Alexandrescu Wrote:

> On 10/14/11 6:08 AM, Jacob Carlborg wrote:
> > On 2011-10-14 12:19, foobar wrote:
> >> Has anyone looked at Nemerle's design for this?
> >> They have an SQL macro which allows to write SQL such as:
> >>
> >> var employName = "FooBar"
> >> SQL (DBconn, "select * from employees where name = $employName");
> >>
> >> what that supposed to do is bind the variable(s) and it also validates
> >> the sql query with the database. This is all done at compile-time.
> >>
> >> My understanding is that D's compile-time features are powerful enough
> >> to implement this.
> >
> > You cannot connect to a database in D at compile time. You could some
> > form of validation and escape the query without connecting to the database.
> 
> A little SQL interpreter can be written that figures out e.g. the names 
> of the columns involved.
> 
> Andrei

The downsides with writing a separate SQL interpreter are:

a) No connection to the DB means no way to validate the schema, e.g. the db might not even have a 'name' column in the employees table. 
b) No way to validate the SQL per the exact version the DB uses. E.g. LIMIT vs. TOP and also DB vendor specific extensions to SQL syntax. 
c) NIH - implementing your own SQL interpreter when the DB vendor already provides it. 

oh, well, perhaps it would be possible with D3 once it supports proper macros. In any case, such a macro probably would be built atop the DB API currently being discussed.