PQclass
connecting Alaska Xbase++ and PostgreSQL
PQclass communicates with a PostgreSQL Server.
The class is based on the C-API of PostgreSQL.
All tables are opened as table objects and are compatible to XClass++.
The class is not limited to a specific version of PostgreSQL. Only the appropriate client DLLs
must be installed:
libpq.dll
libintl.dll
The tables need not to be modified by Alaska Upsize Tool.
PQclass consists of 3 classes:
•
dsPQconnection
Class to setup a connection to a PostgreSQL Server. Login, transaction and global
settings are implemented.
•
dsPQselect
Class for SQL queries. The data is provided by the server and handled by C interface.
Reordering needs to reexecute the query.
•
dsPQdataset
Class that holds the data in a local copy (memory). The resources on the server are
released immediately
Indexing, seeking, filtering is done in the local copy and therefore very fast. The time
to copy the data into the local memory might take more time (depending on network
and amount of data) but subsequent actions will make up for it.
Updates need a primarykey on the table.
Every Update, Insert or Delete will reexecute the query to refresh the copy.
PQclass works with Visual Xbase++ 2.
PostgreSQL
You find all information and downloads about PostgreSQL on www.postgresql.org
In any case take a look into the documentazion.
Important: PostgreSQL is casesensitiv, table and colum names. We recommand to only use
lower case.
PostgreSQL quieres are always a copy of the data at the moment of execution. They never
reflect any changes by any user afterwards. This behaviour differs from DBF tables which
always reflect 'live' data.
