User`s guide
A.2.3.3 Database
The database file consists of one or more tables. Different DBMS applications store database information
differently. For example, dBASE stores each database table as a separate file. Access, on the other
hand, can store several tables, along with queries, macros, and other database elements, all in a single
file.
When Crystal Reports accesses a database file directly, it automatically retrieves information about all
of the tables and fields in that file. You may not use all of the tables or fields, but the program will make
them available to you. In other words, when a dBASE file is opened, only one table in the dBASE file
is available. However, when an Access file is opened, every table in that file is available, even if you
never use them all.
Note:
Crystal Reports will also open queries in an Access database through the DAO engine or ODBC and
will allow you to report on query fields, as with table fields. See DAO and Access.
A.2.4 Common database formats
Although Crystal Reports uses the same three-tiered system for obtaining data from all direct access
database file formats, each format requires a different set of DLLs. However, some formats expand the
basic three-tiered structure.
The following sections cover the systems used by Crystal Reports to access data from some of the
most popular database formats.
A.2.4.1 Microsoft Access
Microsoft Access provides several means for opening its database files. Each method has its advantages
and disadvantages, and the technique that you should use may depend on how your data is set up.
Below is a description of how to open Access data from Crystal Reports through the DAO engine.
Another technique uses Microsoft's Open Database Connectivity (ODBC) standard, and is described
in Access.
Note:
When you open an Access database using the DAO engine, Crystal Reports opens the entire database
and loads information about all tables and queries from the database. To do this, Crystal Reports must
reserve a large section of your computer's memory (called a buffer) in advance.
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Accessing Data Sources