DBIx::DBStag::SQLTemplate(3pm)				User Contributed Perl Documentation			    DBIx::DBStag::SQLTemplate(3pm)

NAME

	 DBIx::DBStag::SQLTemplate - A Template for an SQL query

SYNOPSIS

	 # find template by name
	 $template = $dbh->find_template("mydb-personq");

	 # execute this template, filling in the 'name' attribute
	 $xml = $dbh->selectall_xml(-template=>$template,
				    -bind=>{name => "fred"});

DESCRIPTION

       A template represents a canned query that can be parameterized.

       Templates are collected in directories (in future it will be possible to store them in files or in the db itself).

       To tell DBStag where your templates are, you should set:

	 setenv DBSTAG_TEMPLATE_DIRS "$HOME/mytemplates:/data/bioconf/templates"

       Your templates should end with the suffix .stg, otherwise they will not be picked up

       You can name templates any way you like, but the standard way is to use 2 or 3 fields

	 SCHEMA-OBJECT

       or

	 SCHEMA-OBJECT-QUALIFIERS

       (with underscores used within fields)

       A template file should contain at minimum some SQL; for example:

       Example template 1
	     SELECT
			  studio.*,
			  movie.*,
			  star.*
	     FROM
			  studio NATURAL JOIN
			  movie NATURAL JOIN
			  movie_to_star NATURAL JOIN
			  star
	     WHERE
			  [movie.genre = &genre&] [star.lastname = &lastname&]
	     USE NESTING (set(studio(movie(star))))

	   Thats all! However, there are ways to make your template more useful

       Example template 2
	     :SELECT
			  studio.*,
			  movie.*,
			  star.*
	     :FROM
			  studio NATURAL JOIN
			  movie NATURAL JOIN
			  movie_to_star NATURAL JOIN
			  star
	     :WHERE
			  [movie.genre = &genre&] [star.lastname = &lastname&]
	     :USE NESTING (set(studio(movie(star))))

	     //
	     schema: movie
	     desc: query for fetching movies

	   By including : at the beginning it makes it easier for parsers to assemble SQL (this is not necessary for DBStag however)

	   After the // you can add tag: value data.

	   You should set schema: if you want the template to be available to users of a db that conforms to that schema

   GETTING A TEMPLATE
       The DBIx::DBStag object gives various methods for fetching templates by name, by database or by schema

   VARIABLES
       WHERE clause variables in the template look like this

	 &foo&

       variables are bound at query time

	 my $set = $dbh->selectall_stag(-template=>$t,
					-bind=>["bar"]);

       or

	 my $set = $dbh->selectall_stag(-template=>$t,
					-bind=>{foo=>"bar"});

       If the former is chosen, variables are bound from the bind list as they are found

   OPTIONAL BLOCKS
	 WHERE [ foo = &foo& ]

       If foo is not bound then the part between the square brackets is left out

       Multiple option blocks are ANDed together

       An option block need not contain a variable - if it contains no &variable& name it is automatically ANDed

   BINDING OPERATORS
       The operator can be bound at query time too

	 WHERE [ foo => &foo& ]

       Will become either

	 WHERE foo = ?

       or

	 WHERE foo LIKE ?

       or

	 WHERE foo IN (f0, f1, ..., fn)

       Depending on whether foo contains the % character, or if foo is bound to an ARRAY

METHODS

   name
	 Usage	 - $name = $template->name
	 Returns - str
	 Args	 -

       every template has a name that (should) uniquely identify it

   desc
	 Usage	 - $desc = $template->desc
	 Returns - str
	 Args	 -

       templates have optional descriptions

   get_varnames
	 Usage	 - $varnames = $template->get_varnames
	 Returns - listref of strs
	 Args	 -

       Returns the names of all variable used in this template

WEBSITE

       <http://stag.sourceforge.net>

AUTHOR

       Chris Mungall <cjm@fruitfly.org>

COPYRIGHT

       Copyright (c) 2003 Chris Mungall

       This module is free software.  You may distribute this module under the same terms as perl itself

perl v5.12.4							    2010-02-01					    DBIx::DBStag::SQLTemplate(3pm)