You could also use the DTOS() function, which does the same thing as DTOC(,1), but is more readable. This will make your program logic easier to follow in the future.

DTOC stands for Date TO Character
DTOS stands for Date TO String.

DTOC(,1) gives the same functionality as DTOC(,1), but you need to remember what the ',1' parameter does for you.

Thus the result I would recommend would be

ssnumber + DTOS(orderdate)

>To create a compound index key, you've to convert all fields to the character type.

ssnumber + DTOC(orderdate,1)

Notice the second parameter used in DTOC(,1) function. It converts a date to the text format suitable for an index key.
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>>I am trying to set a primary key for a character field and a date field through an expression. I have thhe following:
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>>ssnumber+orderdate
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>>ssnumber is a character field and the orderdate is a date field. When I try and save it I get the following:
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>>Operator/operand type mismatch
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