What is the relationship between datasources and datasets?

  • I am new to reporting services and have a database named MHC. I used this as a datasource for some reports. I am getting confused now as I used MHC as a dataset as well, and I have an idea of the difference, but not a complete understanding. Could someone explain this to me? Is a dataset really just a SQL Select statement on a larger datasource? Or what? I am using the Reporting Services part of Business Intelligence Development Studio. I complete a report and then upload it to the ReportServer website. That site has datasources, too, and I don't understand the relationship between these two, either. Does this site have to have the same dataources as the report that cam from Business Intelligence Development Studio.

  • The datasource determines which server, and which database to look in for data. If there is already a datasource up on the server pointing to the same database as the one that you want, you can use it, as long as it's shared, and if you want to do subscriptions, it must be set up for it.

    the dataset determines which fields of which tables data will come from, as well as hosting the locig behind the report. The dataset will look for the tables and fields through the datasource.

  • Thank you for your reply. Does that mean that the dataset is actually a SQL statement? And when you are in Business Intelligence Development Studio, and you click on the data tab of a report and see the query behind the report, is that the same SQL as is when you click on Edit dataset? Furthermore, where does the SQL grouping and case statements go? In the dataset?

  • Yes - the dataset is the query. However the actual SQL statement can either be placed directly in Business Intelligence Development Studio under the data tab or it can be executed via a stored procedure (invoked from the same location). Also, there can be multiple datasets which can populate different parts of the report -- including parameters.

  • Just as an addon to the previous reply, the dataset determines what data is returned for use in the report. An of course is the query. A lot of the data handling can also be done in the actual report layout, as mentioned, through parameters, but also through filters, grouping etc. Case, Switch, Iif, etc statements can be used in the tables and textboxes of the report for futher refinement of the data returned by the dataset.

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