A report is one of the interfaces through which users can interact with database systems.
Using reports, the data is visualized and displayed to users. The data can be displayed in many different formats, which will be discussed later in this chapter.
Generally, data reports have the following properties:
- A report can be used only to display data. In contrast to forms-based interfaces, which can be used both to read and modify data, a report is a read-only user interface. You can use reports to view data statically or dynamically.
- A report generator supports many different layouts and file formats. A report presents data in a preformatted form. In other words, you use a report layout to compose items that correspond to result values of the report query. (You can generally design and visualize your reports either in graphical or tabular form.)
- A report is always based on a corresponding SELECT statement. Because reports can be used only to display data, each report is based on a SELECT statement, which retrieves data. The difference between the result of a retrieval operation and the corresponding report is that the latter uses various styles and formats to display data, while the result set of each SELECT statement has a static form, which is arranged by the system.
- A report can use parameters, which are part of a particular query and whose values are set at run time. You can use parameters, as a part of your query, to add flexibility to reports. The values of such parameters are passed from a user or an application program to the query.
- One or more sources always provide input data for the report. A query, which retrieves data, is stored in one or more sources that are usually relational databases, but can be other data sources, too.
Concerning its structure, each report has the following two instruction sets, which together specify the content of the report:
- Data definition Specifies data sources and a dataset. Data sources are all databases and files that provide input data to report, as described. The content of the dataset is the output specified with the corresponding SELECT statement.
- Report layout Enables you to present selected data to users. You can specify which column values correspond to which fields. You can also specify layout details such as the style and location of headings and numbers.
Now that you’ve had this general introduction to reports, you are ready to look at the architecture of SQL Server Reporting Services.
Source: Petkovic Dusan (2020), Microsoft SQL Server 2019: A Beginner’s Guide, Seventh Edition-McGraw-Hill Education.