Using OpenPetra's DataAccess Objects
Purpose of OpenPetra's DataAccess Objects
OpenPetra's DataAccess Objects form an Object-Relational Mapper (ORM [1]). The ORM relieves the programmer from the need to write SQL commands and provides compile-time checks as the DataAccess Objects expose Methods with Typed Arguments. Contrast that with SQL commands, which are simple strings embedded in source code. No compile-time checks (such as for correctness of syntax and existence of a certain DB table) can be done on those!
OpenPetra's DataAccess Objects are auto-generated from the \db\petra.xml file and use the RDMBS-agnostic Database Access Object for the execution of SQL commands (DataAccess Objects are therefore not tied to a specific RDBMS!).
An overview of OpenPetra's DataAccess Objects can be found here.
Reading Data From The Database
Data is read using one of the many Load... Methods of a DataAccess Object.
The following Methods exist:
LoadAll Methods (overloaded)
TODO
LoadByPrimaryKey Methods (overloaded)
TODO
LoadByUniqueKey Methods (overloaded)
TODO
LoadViaForeignKey Methods (overloaded)
TODO
LoadVia... Methods (overloaded)
TODO
LoadVia...Template Methods (overloaded)
TODO
LoadUsingTemplate Methods (overloaded)
TODO
Counting of Data And Checking For Existence of Data In The Database
Counting of Data In The Database
CountAll Method
TODO
CountUsingTemplate Methods (overloaded)
TODO
CountViaForeignKey Methods (overloaded)
TODO
CountVia... Method
TODO
CountVia...Template Methods (overloaded)
TODO
Checking For Existence of Data In The Database
Exists Method
Checks if a row exists with the specified primary key.
Writing And Deleting Data From The Database
SubmitChanges Methods (overloaded)
TODO
AddOrModifyRecord Method
If a record with the specified primary key already exists in the database, that record will be updated, otherwise a new record will be added.
DeleteByPrimaryKey Method
TODO
DeleteUsingTemplate Methods (overloaded)
TODO
Other Functionalities
GetSafeValue Methods (overloaded)(from Ict.Common.Data.TTypedDataAccess)
This Method returns either a valid Object or System.DBNull.
NotEquals Method (from Ict.Common.Data.TTypedDataAccess)
Compares the original and the current value of a DataColumn in a DataRow.
RowCount Property (from Ict.Common.Data.TTypedDataAccess)
Tells how many DataRows are in the current query or have been processed.