Notes on Sub-Reports in Crystal Reports 2008 [Field Notes]

For starters, in CR 2008, you can’t create two separate groups of data in one report (for example, all labor for a work order and then all materials for a work order).

To do this, you need to create a sub-report, format it, and pass any values back up to the main report using shared variables.

This forum post that I found has a great quick run-down on how to accomplish shared variables from sub-reports to main reports. It was very helpful in understanding the wonky Crystal syntax behind what should be a simple thing.

The post is excerpted (though poorly formatted) below in case the originating site ever goes away. NOTE: None of the content below is mine; it is a reproduction because the information was too valuable to lose.

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Shared variables, introduced since Crystal Reports version 7, make it easier to pass values from a sub-report to the main report.

Using shared variables requires two formulas: one to store the value in a shared variable, the other to retrieve the value from the shared variable.

The most important thing to remember when using shared variables is that Crystal Reports must first evaluate the formula where the value is stored before evaluating the formula that retrieves the shared variable. For example if you want to pass a grand total from the sub-report to do a calculation in the main report, follow these steps:

• In the sub-report, create a formula similar to the one below:

// SubFormula

//Stores the grand total of the {Orders.Order Amount} field
//in a currency variable called 'myTotal'

WhilePrintingRecords;
Shared CurrencyVar myTotal := Sum ({Orders.Order Amount})

• Place this formula in your sub-report.
• In the main report, create a formula that declares the same variable name:

//@MainFormula
//Returns the value that was stored in the shared currency variable called
//myTotal in the sub-report

WhilePrintingRecords;
Shared CurrencyVar myTotal;

myTotal

• Place @MainFormula in a main report section that is beneath the section containing the sub-report. For the shared variable to return the correct value in the main report, you must place @MainFormula in a main report section that is beneath the section containing the sub-report. This ensures Crystal Reports evaluates the @SubFormula before @MainFormula.

One way to do this is to insert a section below the section containing the sub-report, and place @MainFormula in this new sub-section:

• On the Format menu, click Section.
• On the Sections list, click the section containing the sub-report.
• Click Insert (at top of dialog box). This inserts an additional subsection.
• Click OK to return to the report, and insert @MainFormula into this new subsection.

The next time you preview the report, @MainFormula displays the value from the sub-report. In this particular example, that value was the grand total of the {Orders.Order Amount} field.

• Once you have verified that @MainFormula is returning the correct value from the sub-report, you can include this formula in other main report formulas, such as:

//@NewFormula
//includes data from sub-report
{@MainFormula}+ Sum ({Customer.Last Year's Sales})

Place this formula in the same section as @MainFormula, or in a section further down on the report.