[PostgreSQL] and [Tcl] combine quite pleasantly.  It can be a delight using them for substantial 
development projects.  Much the more demanding, at least in setup, is the former.  Here's what
it takes to start:  ...
[[to be finished]]

----

Ugh.  I'm left hanging in anticipation...

Seriously, this is a problem I have right now. If the original author (or anybody else) wants to add to this page, it would be *greatly* appreciated.

----

'''1. Setup PostgreSQL'''

Either just install your OS specific package if it is available for example the postgreSQL rpm, or start reading the fine postgreSQL install instructions at:
http://www.postgresql.org/docs/7.4/interactive/installation.html

Make sure you have a running server, get its connection info like hostname, port, user and password for the user you want to use for the next steps.

'''2. Make sure you have a working Pgtcl package'''

Try:
 package require Pgtcl

If it works, you have a probably working Pgtcl package installed, otherwise you need to install/compile one from either the PostgreSQL distribution you have installed (Pgtcl should be included there) or obtain and build [libpgtcl].

'''3. Start using Pgtcl'''

Take a look at:
http://www.postgresql.org/docs/7.4/interactive/pgtcl.html

The basics:

 # select and do something with the results...
 # open connection
 # password etc. must be provided according to the security settings on the postgres db
 # you may be able to just do "pg_connect www" or even "pg_connect" if database is your username

 package require Pgtcl

 set db [pg_connect -conninfo [list host = localhost user = test dbname = testdb]

    pg_select $conn "select * from testtable" user {
        parray user
    }

    pg_disconnect $db

Inserting into a database...  Note how pg_exec returns a result handle that
has many things that can be done with it to access the results.   You can
get a list interactively by doing a pg_result with no arguments.  You gotta
clean up the result handle this way.  Note that pg_select, above, takes
care of all that for you.

 package require Pgtcl

 proc doit {} {
     set fp [open sampledata.txt]
     set conn [pg_connect -conninfo ""]

     while {[gets $fp line] >= 0} {
         lassign $line name address city state zip

         set statement "insert into peopletable values ( \
            [pg_quote $name], [pg_quote $address], [pg_quote $city] \
            [pg_quote $state], [pg_quote $zip]);"

        set result [pg_exec $conn $statement]
        if {[pg_result $result -status] != "PGRES_COMMAND_OK"} {
            puts "[pg_result $result -error] executing '$statement'"
        }
        pg_result $result -clear
    }
 }

 if !$tcl_interactive doit

Recent version of Pgtcl running with fairly recent version of PostgreSQL can
do variable substitutions, which are pretty cool, and require less quoting
and stuff.  Observe...

         set statement "insert into peopletable values ($1, $2, $3, $4, $5);"

        set result [pg_exec $conn $statement $name $address $city $state $zip]

'''4. Pgtcl Commands'''

pg_quote

This escapes a string by making it Postgres-safe.  It quotes single
quotes and backslashes.  If you're doing something like

 pg_exec "insert into foo(name='$name');"

 and name contains a single
quote, it'll fail.  Passign value strings through pg_quote
make sure they can be used as values and stuff in Postgres.

 pg_exec "insert into foo(name=[pg_quote $name]);" 

will make
sure that any special characters that occur in name, such as
single quote or backslash, will be properly quoted.

pg_connect -conninfo conninfoString

    The modern way to connect, all necessary information required for
    the connection (host, port, database, user, password, etc.) is
    specified in the connect info string.


 pg_disconnect connection

Close a backend connection.

 pg_exec connection query

Send a query string to the backend connection.

The return result is either an error message or a handle for a query result.
Handles start with the prefix "pgp".


pg_select

Send a select query string to the backend connection.

         pg_select connection query arrayName code

The query must be a select statement.  The code is run once for each row found.
See the example earlier in this page.

 
You can "continue" and "return" in the body and it'll do the expected thing.
(What I think is expected, anyway.)

pg_result

Get information about the results of a query.

    pg_result result ?option?

The options are:

        -status         the status of the result

        -error          the error message, if the status indicates error;
                             otherwise an empty string

        -conn           the connection that produced the result

        -oid            if command was an INSERT, the OID of the inserted tuple

        -numTuples      the number of tuples in the query

        -numAttrs       returns the number of attributes returned by the query

        -assign arrayName
                        assign the results to an array, using
                            subscripts of the form (tupno,attributeName)

        -assignbyidx arrayName ?appendstr?
                        assign the results to an array using the first
                            field's value as a key.

                        All but the first field of each tuple are stored,
                            using subscripts of the form
                            (field0value,attributeNameappendstr)

        -getTuple tupleNumber
                        returns the values of the tuple in a list 
    
        -tupleArray tupleNumber arrayName
                        stores the values of the tuple in array arrayName,
                            indexed by the attributes returned

        -attributes     returns a list of the name/type pairs of the tuple
                            attributes

        -lAttributes    returns a list of the {name type len} entries of the
                            tuple attributes

        -clear          clear the result buffer. Do not reuse after this