Re: [Tcl-tdbc] TDBC documentation, samples

[Kevin K. <kk...@ny...>]

Patrick Dunnigan wrote:
> Hi, I have read tip 308 and various other web pages but can’t seem to 
> find any comprehensive documentation on the use of TDBC and the small 
> bits of example code that I have found seem to be conflicting. I can 
> help with the testing effort but need some information on how to use 
> TDBC in my scripts.

Unfortunately, there isn't very much tutorial information out there.
The manual pages *are* there, and if you install drivers (which you
have to do to actually *use* tdbc) their manual pages will be there,
too.  308 didn't change very much between TIP and implementation, but
I agree that TIP prose isn't the easiest thing in the world to read.

How far have you got?  I don't think that an email thread is the best
place to start developing a tutorial, but perhaps we can Wikify the
missing knowledge and whack it into a decent form. That will be easiest
to do starting from specific questions.

In any case, if you haven't already, you need to:

     (a) Either have 8.6b1 (or later), or else have 8.5 plus the
         tcloo extension and the tdbc extension.

     (b) Have a SQL database that you can use.  Windows users always
         have Jet (the engine underlying Microsoft Access) available,
         even if they haven't bought Access.  SQLite runs everywhere.
         And TDBC has a MySQL driver.

     (c) Have the driver for the database.  Windows users can get
         binaries for the drivers that are so far available (ODBC,
         MySQL and SQLite3) from http://preview.tinyurl.com/db2zw8
         Unix users at this point still have to build from source.
         Source ZIPs are available from http://tdbc.tcl.tk/

     (d) Once you have a driver built and operational, or if you
         get stuck, start asking questions!  There isn't that much
         there, but I've probably neglected to document some key
         piece that's making you stumble.

A summary example will give the basic idea:

tdbc::sqlite3::connection create db /path/to/my/database.sql
db allrows {
     CREATE TABLE people(
         name VARCHAR(40),
         phone VARCHAR(16)
     )
}
set stmt [db prepare {
     INSERT INTO people(name, phone) VALUES(:name, :phone)
}]
foreach {name phone} {
     fred 555-1234
     barney 555-1235
     wilma 555-1234
     betty 555-1235
} {
     $stmt allrows
}
$db foreach row {SELECT phone FROM people where NAME='fred'} {
     if {[dict exists $row phone]} {
         puts $phone
     } else {
         puts "fred has no phone"
     }
}
$db close