How to ignore duplicates in recordset of Crystal Reports

Say I have a result set with these values:

orderID typeofSale

A1 Sell

A1 Buy

B1 Sell

C1 Sell

The total number of orders here is 3, as A1 got divided. How can this be calculated in Crystal?

I tried looping through the orders with WhileReadingRecords; and maintaining the order ids read in an array, and then checking of the order id had already been read, thus not double counting. However, Crystal has an array limitati开发者_开发百科on of 1000 records only....

I've been struggling with this. For some reason, the prev report creator wants this value in the report header, making it all the more difficult.

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You can use DistinctCount

In a formula you would do:

DistinctCount({Table.Yourfield})

Or from the menu Insert > Summary then choose the field you want summarize and select Distinct Count from the Calculate this summary drop down.