Subtraction, concatenation, unary negative operator.


n - m

date - n

date - date

"str1" - "str2"

"str" - x

x - "str"



The "minus" operator is similar to the "plus" operator. It subtracts two numbers, and subtracts days from a date. You may also subtract one date from another date; the result is the number of days between the two dates. If you subtract a blank date from another date, the result is always zero.

The minus symbol is also used as the unary negation operator, to change the sign of a numeric value.

You may concatenate two strings, or a string with any other data type, just like with the plus operator. The difference is that with the minus operator, the trailing blanks from the first operand are removed before the concatenation, and placed at the end of the result. This means that the concatenation with either the plus or minus results in a string with the same length, but with the minus operator, the trailing blanks are combined at the end of the result.

If you want to trim field values when creating an expression index for a DBF table, use the minus operator.