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DBIx::Class::Manual::Glossary(3)     User Contributed Perl Documentation    DBIx::Class::Manual::Glossary(3)



NAME
       DBIx::Class::Manual::Glossary - Clarification of terms used.

INTRODUCTION
       This document lists various terms used in DBIx::Class and attempts to explain them.

DBIx::Class TERMS
   DB schema
       Refers to a single physical schema within an RDBMS. Synonymous with the terms 'database', for MySQL;
       and 'schema', for most other RDBMS(s).

       In other words, it's the 'xyz' _thing_ you're connecting to when using any of the following DSN(s):

         dbi:DriverName:xyz@hostname:port
         dbi:DriverName:database=xyz;host=hostname;port=port

   Inflation
       The act of turning database row data into objects in language-space. DBIx::Class result classes can
       be set up to inflate your data into perl objects which more usefully represent their contents. For
       example: DBIx::Class::InflateColumn::DateTime for datetime or timestamp column data.

       See also DBIx::Class::InflateColumn.

   Deflation
       The opposite of "Inflation". Existing perl objects that represent column values can be passed to
       DBIx::Class methods to store into the database. For example a DateTime object can be automatically
       deflated into a datetime string for insertion.

       See DBIx::Class::InflateColumn and other modules in that namespace.

   ORM
       Object-relational mapping, or Object-relationship modelling. Either way it's a method of mapping the
       contents of database tables (rows), to objects in programming-language-space. DBIx::Class is an ORM.

   Relationship
       In DBIx::Class a relationship defines the connection between exactly two tables. The relationship
       condition lists the columns in each table that contain the same values. It is used to output an SQL
       JOIN condition between the tables.

   Relationship bridge
       A relationship bridge, such as "many_to_many" defines an accessor to retrieve row contents across
       multiple relationships.

       The difference between a bridge and a relationship is, that the bridge cannot be used to "join"
       tables in a "search", instead its component relationships must be used.

   Schema
       A Schema object represents your entire table collection, plus the connection to the database. You can
       create one or more schema objects, connected to various databases, with various users, using the same
       set of table "Result class" definitions.

       At least one DBIx::Class::Schema class is needed per database.

   Result class
       A Result class defines both a source of data (usually one per table), and the methods that will be
       available in the "Row" objects created using that source.

       One Result class is needed per data source (table, view, query) used in your application, they should
       inherit from DBIx::Class::Core.

   ResultSource
       ResultSource objects represent the source of your data, these are sometimes (incorrectly) called
       table objects.

       ResultSources do not need to be directly created, a ResultSource instance is created for each "Result
       class" in your "Schema", by the proxied methods "table" and "add_columns".

       See also: "METHODS" in DBIx::Class::ResultSource

   ResultSet
       This is an object representing a set of conditions to filter data. It can either be an entire table,
       or the results of a query. The actual data is not held in the ResultSet, it is only a description of
       how to fetch the data.

       See also: "METHODS" in DBIx::Class::ResultSet

   Record
       See Row.

   Row
       Row objects contain your actual data. They are returned from ResultSet objects.

   Object
       See Row.

   join
   prefetch
SQL TERMS
   Join
       This is an SQL keyword, it is used to link multiple tables in one SQL statement. This enables us to
       fetch data from more than one table at once, or filter data based on content in another table,
       without having to issue multiple SQL queries.

   Normalisation
       A normalised database is a sane database. Each table contains only data belonging to one concept,
       related tables refer to the key field or fields of each other. Some links to webpages about
       normalisation can be found in DBIx::Class::Manual::FAQ.

   Related data
       In SQL, related data actually refers to data that are normalised into the same table. (Yes. DBIC does
       mis-use this term).



perl v5.12.5                                     2010-11-29                 DBIx::Class::Manual::Glossary(3)