Understanding the Different Join Types

In Crystal Reports, the Link tab of the Report Wizard (and Database Expert) provides a visual representation of the relationship between multiple database objects. Defining the appropriate join strategy for any given report should be reflective of the data within the database objects and of how the report needs to read and display that data. Join type settings enable you to control more precisely the query results based on your unique requirements. The following is a list of the most common types of joins and their associated descriptions:

NOTE

The capability to enforce links created in a report is new to version 10. Enforcing a link between two tables ensures that this link will be used in the report's respective SQL, regardless of whether fields are required from either or both of the involved tables. The default setting is Un-enforced links, meaning that the link will only be used if the report's respective SELECT statement requires it. Access to the different enforcing options is provided by right-clicking on a link and selecting the Link Options menu item.

After a report is created, select Database Expert from the Database menu to return to the Data Explorer. Here tables and SQL Commands can be added, removed, and renamed just as they could from the Data Explorer in the report creation process.

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