Dynamic Datasources

Dynamic Datasources

When you define a report, you specify the datasource from which data will be retrieved. Sometimes, you may have several databases that have the same schema but contain different data e.g. a live production database, a test database, a database that has data as at end of month etc. You may want to have the possibility of running the same query over these different databases. Rather than creating several reports with identical sql but different datasources, you can create one report and have the datasource as a parameter that can be selected at runtime. This eliminates the work of creating multiple reports and makes management of the relevant sql much easier - if you need to change the sql, you only have to do it in one place. The process of using dynamic datasources is as follows.

• Create a datasource for each of your target databases
• Create the report that will retrieve the data you want. What you select in the Datasource field is not important as the report will use a dynamically specified datasource. It is advisable though to set this to a valid, default datasource for your sql.
• Define a single-value parameter for your report, setting the Data Type to Datasource. If you would like the available datasources to be selected from a list, create and specify the LOV report that will display the desired datasources.

When you run the report, it will use the value of the datasource parameter to determine which datasource to run the report on. The value of this parameter should be a datasource id or datasource name. If it passes the "isNumeric" test, it will be assumed that it is referring to a datasource id, otherwise a check against datasource names will be done.