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Do you wonder exactly what goes on between the time you choose a data source and the time the data appears in your report? The Database Expert is a powerful interface for connecting to a wide variety of data sources. When you build a new report, one of the very first decisions you need to make is which data source to use. From there, Crystal does the rest of the legwork to retrieve the data you specified. The wizard approach provided by the Database Expert hides the entire complex nature and the gory details of database connection and data retrieval from you. While this may be a good thing most of the time, we all know that too much of a good thing can also cause some grief. In this case, choosing one data source over another may work against you when optimum data retrieval performance is your goal.
To help you achieve the best retrieval speeds, you can use Structured Query Language (SQL) within Crystal Reports. In Chapter 10, “Data Sources and the Database Expert,” we touched on the concept of personal computer (PC)–type databases versus client/server databases. We will continue this discussion in this chapter so that you may better understand the role that SQL plays in Crystal Reports. SQL is a command syntax used exclusively with relational databases. Some databases support this language; others do not. If a report designer chooses a SQL-capable database, Crystal can use a subset of this language to retrieve data efficiently from SQL-capable databases. To this end, you need to get a good handle on the structure and use of SQL statements and where in Crystal Reports you can make use of this knowledge.
Featured in this chapter:
Choosing client/server databases versus PC-type databases
Understanding Structured Query Language
Using SQL expression fields
Using SQL commands as a data source
Creating stored procedures
Creating views
Using Crystal Reports database utilities
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