THIS IS A TEST INSTANCE. ALL YOUR CHANGES WILL BE LOST!!!!
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For example, consider a database with the following table:
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TABLECUSTOMER ID INTEGER LASTNAME CUSTOMER ID INTEGER LASTNAME VARCHAR(20) ADDRESS ADDRESS VARCHAR(30) |
If an application uses the DAS to query this table with the following SQL statement:
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The DAS will return a graph of DataObjects each of Type CUSTOMER and each instance in will have three properties: (ID, LASTNAME, ADDRESS). Here is the example code. Note that no configuration data is provided at all.
| Code Blockpanel |
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DAS das = DAS.FACTORY.createDAS(getConnection());
readCustomers = das.createCommand("select * from CUSTOMER");
root = readCustomers.executeQuery(); |
Another piece of convention followed by the RDB DAS has to do with database table keys. When asked to "apply changes", the RDB DAS scans the SDO ChangeSummery and generates the set of INSERT/UPDATE and DELETE statements needed to flush the graph changes to the database. To generate the correct statements the RDB DAS needs to know how a DataObject's properties map to a database table key. In typical Object/Relational mappings frameworks, this information is provided in a config file with something like this:
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