Software Platform User guide

For more information
•
To create enhanced parameters, see Advanced parameter features.
•
For general information about parameter fields, see Parameter and prompt
overview .
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For general details regarding record selection formulas, see Record
Selection.
Using SQL expressions where appropriate
SQL expressions are like formulas, but they are written in Structured Query
Language (SQL). They are useful in optimizing report performance because
the tasks they execute are normally performed on the database server (as
opposed to a regular formula, which is sometimes executed on the local
machine).
Don't use SQL expressions exclusively, because Crystal Reports includes
its own formula language, which is much more powerful than standard SQL.
Both Crystal Syntax and Basic Syntax allow you to enhance and hone your
formulas in ways that are either difficult or impossible with SQL. In certain
circumstances, however, creating and using SQL Expression fields can
speed up the processing of your reports.
Key uses of SQL Expression fields
To maintain optimum report processing speeds, avoid using formulas
(whether Crystal or Basic syntax) within record selection formulas. Instead,
replace the original formula with an equivalent SQL Expression field, and
then incorporate the SQL Expression field into your record selection formula.
Doing so will greatly improve the chances of your record selection being
pushed down to the server.
In addition, avoid sorting, grouping, or totaling on a formula field (whether
Crystal or Basic syntax). Instead, replace the original formula field with an
equivalent SQL Expression field, and then sort, group, or total on the SQL
Expression Field. Again, this will greatly improve the chances of the
processing being done on the server.
Crystal Reports 2008 SP3 User's Guide 185
8
Designing Optimized Web Reports
Using enhanced record selection formulas