--- name: "DBIx::DBSchema::DBD" section: "3pm" platform: "linux" package: "libdbix-dbschema-perl" version: "0.47-1" release: "Debian 13 (Trixie)" platforms: ["linux"] url: "https://new.carta.tech/DBIx::DBSchema::DBD" --- # DBIx::DBSchema::DBD(3pm) DBIx::DBSchema Driver Writer's Guide and Base Class ## NAME DBIx::DBSchema::DBD - DBIx::DBSchema Driver Writer's Guide and Base Class ## SYNOPSIS ``` perldoc DBIx::DBSchema::DBD package DBIx::DBSchema::DBD::FooBase use DBIx::DBSchema::DBD; @ISA = qw(DBIx::DBSchema::DBD); ``` ## DESCRIPTION Drivers should be named DBIx::DBSchema::DBD::DatabaseName, where DatabaseName is the same as the DBD:: driver for this database. Drivers should implement the following class methods: - columns CLASS DBI\_DBH TABLE Given an active DBI database handle, return a listref of listrefs (see perllol), each containing six elements: column name, column type, nullability, column length, column default, and a field reserved for driver-specific use. - column CLASS DBI\_DBH TABLE COLUMN Same as **columns** above, except return the listref for a single column. You can inherit from DBIx::DBSchema::DBD to provide this function. - primary\_key CLASS DBI\_DBH TABLE Given an active DBI database handle, return the primary key for the specified table. - unique CLASS DBI\_DBH TABLE Deprecated method - see the **indices** method for new drivers. Given an active DBI database handle, return a hashref of unique indices. The keys of the hashref are index names, and the values are arrayrefs which point a list of column names for each. See "HASHES OF LISTS" in perldsc and DBIx::DBSchema::Index. - index CLASS DBI\_DBH TABLE Deprecated method - see the **indices** method for new drivers. Given an active DBI database handle, return a hashref of (non-unique) indices. The keys of the hashref are index names, and the values are arrayrefs which point a list of column names for each. See "HASHES OF LISTS" in perldsc and DBIx::DBSchema::Index. - indices CLASS DBI\_DBH TABLE Given an active DBI database handle, return a hashref of all indices, both unique and non-unique. The keys of the hashref are index names, and the values are again hashrefs with the following keys: - name - Index name (redundant) - using - Optional index method - unique - Boolean indicating whether or not this is a unique index - columns - List reference of column names (or expressions) (See FS::DBIx::DBSchema::Index) New drivers are advised to implement this method, and existing drivers are advised to (eventually) provide this method instead of **index** and **unique**. For backwards-compatibility with current drivers, the base DBIx::DBSchema::DBD class provides an **indices** method which uses the old **index** and **unique** methods to provide this data. - default\_db\_catalog Returns the default database catalog for the DBI table\_info command. Inheriting from DBIx::DBSchema::DBD will provide the default empty string. - default\_db\_schema Returns the default database schema for the DBI table\_info command. Inheriting from DBIx::DBSchema::DBD will provide the default empty string. - constraints CLASS DBI\_DBH TABLE Given an active DBI database handle, return the constraints (currently, foreign keys) for the specified table, as a list of hash references. Each hash reference has the following keys: - constraint - contraint name - columns - List refrence of column names - table - Foreign taable name - references - List reference of column names in foreign table - match - - on\_delete - - on\_update - - column\_callback DBH TABLE\_NAME COLUMN\_OBJ Optional callback for driver-specific overrides to SQL column definitions. Should return a hash reference, empty for no action, or with one or more of the following keys defined: effective\_type - Optional type override used during column creation. explicit\_null - Set true to have the column definition declare NULL columns explicitly effective\_default - Optional default override used during column creation. effective\_local - Optional local override used during column creation. - add\_column\_callback DBH TABLE\_NAME COLUMN\_OBJ Optional callback for additional SQL statments to be called when adding columns to an existing table. Should return a hash reference, empty for no action, or with one or more of the following keys defined: effective\_type - Optional type override used during column creation. effective\_null - Optional nullability override used during column creation. sql\_after - Array reference of SQL statements to be executed after the column is added. - alter\_column\_callback DBH TABLE\_NAME OLD\_COLUMN\_OBJ NEW\_COLUMN\_OBJ Optional callback for overriding the SQL statments to be called when altering columns to an existing table. Should return a hash reference, empty for no action, or with one or more of the following keys defined: sql\_alter - Alter SQL statement(s) for changing everything about a column. Specifying this overrides processing of individual changes (type, nullability, default, etc.). sql\_alter\_type - Alter SQL statement(s) for changing type and length (there is no default). sql\_alter\_null - Alter SQL statement(s) for changing nullability to be used instead of the default. - column\_value\_needs\_quoting COLUMN\_OBJ Optional callback for determining if a column's default value require quoting. Returns true if it does, false otherwise. ## TYPE MAPPING You can define a `%typemap` array for your driver to map "standard" data types to database-specific types. For example, the MySQL TIMESTAMP field has non-standard auto-updating semantics; the MySQL DATETIME type is what other databases and the ODBC standard call TIMESTAMP, so one of the entries in the MySQL `%typemap` is: ``` 'TIMESTAMP' => 'DATETIME', ``` Another example is the Pg `%typemap` which maps the standard types BLOB and LONG VARBINARY to the Pg-specific BYTEA: ``` 'BLOB' => 'BYTEA', 'LONG VARBINARY' => 'BYTEA', ``` Make sure you use all uppercase-keys. ## AUTHOR Ivan Kohler \ ## COPYRIGHT Copyright (c) 2000-2005 Ivan Kohler Copyright (c) 2007-2017 Freeside Internet Services, Inc. All rights reserved. This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself. ## BUGS ## SEE ALSO DBIx::DBSchema, DBIx::DBSchema::DBD::mysql, DBIx::DBSchema::DBD::Pg, DBIx::DBSchema::Index, DBI, DBI::DBD, perllol, "HASHES OF LISTS" in perldsc