From 60a14a9eada33984f8f259e082b5e621270ac8d1 Mon Sep 17 00:00:00 2001 From: Boris Kolpackov Date: Tue, 27 Sep 2011 11:35:29 +0200 Subject: Add view example --- view/README | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) create mode 100644 view/README (limited to 'view/README') diff --git a/view/README b/view/README new file mode 100644 index 0000000..108d234 --- /dev/null +++ b/view/README @@ -0,0 +1,68 @@ +This example shows how to declare and use views in ODB. It includes views +that show how to load a subset of data member from objects and tables, +perform aggregate queries, and join multiple objects and tables using +object relationships and custom join conditions. + +The example uses the shared_ptr smart pointer from TR1 and requires a C++ +compiler with TR1 support or an external TR1 implementation, such as the +one provided by Boost. + +The example consists of the following files: + +employee.hxx + Header file defining the 'country', 'employer', and 'employee' persistent + classes. The example also uses a "legacy" 'employee_extra' table that is + not mapped to a persistent class. + + After the persistent classes, this header defines a number of views that + show how to obtain various information from the above object model. + +employee-odb.hxx +employee-odb.ixx +employee-odb.cxx +employee.sql + The first three files contain the database support code and the last file + contains the database schema for the employee.hxx header. + + These files are generated by the ODB compiler from employee.hxx using the + following command line: + + odb -d --generate-schema --generate-query \ + --default-pointer std::tr1::shared_ptr employee.hxx + + Where stands for the database system we are using, for example, + 'mysql'. + + The --default-pointer option is used to make TR1 shared_ptr the default + object pointer. + +database.hxx + Contains the create_database() function which instantiates the concrete + database class corresponding to the database system we are using. + +driver.cxx + Driver for the example. It includes the employee.hxx and employee-odb.hxx + headers to gain access to the persistent classes and their database support + code. It also includes database.hxx for the create_database() function + declaration. + + In main() the driver first calls create_database() to obtain the database + instance. It then creates the legacy 'employee_extra' table and proceeds + to populate the database with a number of 'employee', 'employer', and + 'project' objects. Once this is done, the driver uses views defined in + employee.hxx to load and print various information about the object model. + +To run the example we may first need to create the database schema (for some +database systems, such as SQLite, the schema is embedded into the generated +code which makes this step unnecessary). Using MySQL as an example, this +can be achieved with the following command: + +mysql --user=odb_test --database=odb_test < employee.sql + +Here we use 'odb_test' as the database login and also 'odb_test' as the +database name. + +Once the database schema is ready, we can run the example (using MySQL as +the database): + +./driver --user odb_test --database odb_test -- cgit v1.1