MQdb::Database3pm

Overview

Generalized handle on an DBI database handle. Used to provide an instance which holds connection information and allows a higher level get_connection/ disconnect logic that persists above the specific DBI connections. Also provides a real object for use with the rest of the toolkit.

Summary

MQdb::Database provides the foundation of the MappedQuery system. Databases are primarily specified with a URL format. The URL format includes specification of a driver so this single method can select among the supported DBD drivers. Currently the system supports MYSQL, Oracle, and SQLite. The URL also allows the system to provide the foundation for doing federation of persisted objects. Each DBObject contains a pointer to the Database instance where it is stored. With the database URL and internal database ID, each object is defined in a global space.

Attributes of MQdb::Database
driver : mysql, oracle, sqlite (default mysql)
user : username if the database requires
password : password if the database requires
host : hostname of the database server machine
port : IP port of the database if required
(mysql default is 3306)
dbname : database/schema name on the database server
for sqlite, this is the database file

Example URLS
mysql://<user>:<pass>@<host>:<port>/<database_name>
mysql://<host>:<port>/<database_name>
mysql://<user>@<host>:<port>/<database_name>
mysql://<host>/<database_name>
oracle://<user>:<pass>@/<database_name>
oracle://<user>:<pass>@<host>:<port>/<database_name>
sqlite:///<database_file>

Contact

Jessica Severin <[email protected]>

Appendix

The rest of the documentation details each of the object methods. Internal methods are usually preceded with a _

  Description: instance creation method
  Parameter  : a hash reference of options same as attribute methods
  Returntype : instance of this Class (subclass)
  Exceptions : none

  Description: instance creation method
  Returntype : instance of this Class (subclass)
  Exceptions : none

  Description: initialization method which subclasses can extend
  Returntype : $self
  Exceptions : subclass dependent

  Description: primary instance creation method
  Parameter  : a string in URL format
  Returntype : instance of MQdb::Database
  Examples   : my $db = MQdb::Database->new_from_url("mysql://<user>:<pass>@<host>:<port>/<database_name>");
               e.g. mysql://<host>:<port>/<database_name>
               e.g. mysql://<user>@<host>:<port>/<database_name>
               e.g. mysql://<host>/<database_name>
               e.g. sqlite:///<database_file> 
  my $class = shift;
  Exceptions : none

  Description: makes a copy of the database configuration.
               New instance will have its own database connection 
  Returntype : instance of MQdb::Database

  Description: connects to database and returns a DBI connection
  Returntype : DBI database handle
  Exceptions : none

  Description: disconnects handle from database, but retains object and 
               all information so that it can be reconnected again 
               at a later time.
  Returntype : none
  Exceptions : none

  Description: returns the URL of this database with user and password
  Returntype : string
  Exceptions : none

  Description: returns URL of this database but without user:password
               used for global referencing and federation systems
  Returntype : string
  Exceptions : none

  Description: returns XML of this database but without user:password
               used for global referencing and federation systems
  Returntype : string
  Exceptions : none

  Description    : executes SQL statement with external parameters and placeholders
  Example        : $db->execute_sql("insert into table1(id, value) values(?,?)", $id, $value);
  Parameter[1]   : sql statement string
  Parameter[2..] : optional parameters for the SQL statement
  Returntype     : none
  Exceptions     : none

  Description    : executes SQL statement with "do" and no external parameters
  Example        : $db->do_sql("insert into table1(id, value) values(null,'hello world');");
  Parameter      : sql statement string with no external parameters
  Returntype     : none
  Exceptions     : none

  Arg (1)    : $sql (string of SQL statement with place holders)
  Arg (2...) : optional parameters to map to the placehodlers within the SQL
  Example    : $value = $self->fetch_col_value($db, "select some_column from my_table where id=?", $id);
  Description: General purpose function to allow fetching of a single column from a single row.
  Returntype : scalar value
  Exceptions : none
  Caller     : within subclasses to easy development