Difference between revisions of "Microsoft Access Backend"
Line 51: | Line 51: | ||
==== Methods ==== | ==== Methods ==== | ||
+ | |||
===== update ===== | ===== update ===== | ||
Line 63: | Line 64: | ||
getBackend.update | getBackend.update | ||
</syntaxhighlight> | </syntaxhighlight> | ||
+ | |||
===== relink ===== | ===== relink ===== | ||
Line 77: | Line 79: | ||
getBackend.relink | getBackend.relink | ||
</syntaxhighlight> | </syntaxhighlight> | ||
+ | |||
===== amendConnections ===== | ===== amendConnections ===== | ||
− | + | Backend objects can be accessed through three different connection types. | |
+ | If a connection is provided manually or has been automatically retrieved from a linked object, | ||
+ | naturally the other two connection types are missing. | ||
+ | |||
+ | The amendConnections method scans all connections, looks for missing connections regarding | ||
+ | the connection type and creates the missing connections. | ||
+ | |||
+ | <syntaxhighlight lang="vb"> | ||
+ | amendBackend | ||
+ | 'or | ||
+ | getBackend.amendConnections | ||
+ | </syntaxhighlight> | ||
+ | |||
===== linkTable ===== | ===== linkTable ===== | ||
+ | The developer should not have to worry about connection information like connection strings, | ||
+ | user credentials and other details. | ||
+ | |||
+ | The linkTable method links a backend object into the current frontend. | ||
+ | |||
+ | <syntaxhighlight lang="vb"> | ||
+ | linkBackendTable strTable:="USER", lngServerId:=BackendServer.Oracle | ||
+ | 'or | ||
+ | getBackend.linkTable strTable:="USER", lngServerId:=BackendServer.Oracle | ||
+ | </syntaxhighlight> | ||
+ | |||
+ | The ServerId is realized as Enumeration in order to make backend servers easier accessible. | ||
===== refreshOdbcTables ===== | ===== refreshOdbcTables ===== | ||
+ | Tables which are linked via ODBC unfortunately do not automatically reflect the changes | ||
+ | on the source object. | ||
+ | |||
+ | The refreshOdbcTables method refreshes the ODBC connection and makes the changes visible. | ||
+ | |||
+ | <syntaxhighlight lang="vb"> | ||
+ | refreshOdbcTables | ||
+ | 'or | ||
+ | getBackend.refreshOdbcTables | ||
+ | </syntaxhighlight> | ||
=== Backend Connection === | === Backend Connection === |
Revision as of 01:19, 5 August 2012
General
It is good practice to separate a frontend from a backend, ie to put queries, forms, reports and the business logic into a frontend database and all tables into a backend database no matter what kind of database it is.
Architecture
Server
Every backend is a server no matter whether it is a Microsoft Jet or another type of database. Each server has a unique name.
Location
Development does not happen on the same machine all the time. The location is derived from the workstation name.
Environment
There are usually three environments, namely
- Development
- Testing / Pre-Production
- Production
ConnectionType
Databases can be accessed through different types of connections like
- Jet
- ODBC
- OLEDB
Model
Backend
Properties
The backend class has collections for each architectural aspect:
<uml class style="plain" scale="75" direction="lr"> [Backend]1-*>[ConnectionTypes] [Backend]1-*>[Environments] [Backend]1-*>[Locations] [Backend]1-*>[Servers] </uml>
It also knows all known connections as well as its tables and queries:
<uml class style="plain" scale="75" direction="lr"> [Backend]1-*>[Queries] [Backend]1-*>[Tables] [Backend]1-*>[Connections] </uml>
Methods
update
The backend object does not automatically reflect changes of the backend database.
The update method updates all objects and checks whether the existing linked objects are identifyable.
updateBackend
'or
getBackend.update
relink
Relinking all backend database objects to reflect the current location and environment can become a tedious task, if many objects are linked.
The relink method checks for each linked object which connection is currently present, tries to adjust the connection towards the current location and environment and reconnects the object accordingly.
relinkBackend
'or
getBackend.relink
amendConnections
Backend objects can be accessed through three different connection types. If a connection is provided manually or has been automatically retrieved from a linked object, naturally the other two connection types are missing.
The amendConnections method scans all connections, looks for missing connections regarding the connection type and creates the missing connections.
amendBackend
'or
getBackend.amendConnections
linkTable
The developer should not have to worry about connection information like connection strings, user credentials and other details.
The linkTable method links a backend object into the current frontend.
linkBackendTable strTable:="USER", lngServerId:=BackendServer.Oracle
'or
getBackend.linkTable strTable:="USER", lngServerId:=BackendServer.Oracle
The ServerId is realized as Enumeration in order to make backend servers easier accessible.
refreshOdbcTables
Tables which are linked via ODBC unfortunately do not automatically reflect the changes on the source object.
The refreshOdbcTables method refreshes the ODBC connection and makes the changes visible.
refreshOdbcTables
'or
getBackend.refreshOdbcTables