Re: [Caml-list] Dbi: proposal #1

[Richard Jones <rich@annexia.org>]

On Tue, Jun 10, 2003 at 10:10:41PM +0200, Christophe TROESTLER wrote:
> Some sample code:
> 
>   module DB = Dbi_mysql  (* select db module *)
>   let t = new DB.row_conversion
>   let ( ++ ) = Dbi.(^^)
> 
>   let dbh = DB.connect ~host ~pwd "my database" in
>   let q = dbh#prepare "SELECT Salary, Name from employees" in
>   let res = dbh#raw_exec q [||] in
>   let s = res#fold (t#int ++ t#string) (fun sum s _ -> sum + s) 0 in
>   dbh#disconnect;
>   s

I wish I knew enough OCaml to make some really insightful comments
about this, but in general it looks OK. One question: do you provide
placeholders in the string argument to prepare, eg:

let query = dbh#prepare "select salary from employees where salary < ?" in
let res = query#execute 10000 in
...

(Note I couldn't really understand why you would call dbh#raw_exec
instead of some method on query itself, so I changed that).

To make this type-safe you might need to add type information to the
placeholders, eg. "select ... where salary < ?:int"

Rich.

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