$$(expression) specifies numeric, logical (boolean) or date/time expression.

An expression can contain:

  • Numeric constants and quoted strings (example: 'null')
  • Function calls
  • Date or time constants created by $Date or $Time function
  • Operations ('+','-','*','/') and comparison operators ('>','>=','<','<=','=', '!=')
  • '&' and '|' for AND and OR logicals operators


Operations '*','/' and unary '-' are acceptable for numeric operands only.

Only comparison operations can be applied to strings.

Logical operations '>','>=','<','<=','=','!=' are acceptable for numeric, date and time operands.

'&' and '|' are acceptable for logical (boolean) operands only.

The '+' operation

Right operand
Left operandIntegerFloatDateTime
Integer++ (float)Add N daysAdd N seconds
Float+ (float)+N/AN/A
Dateadd N daysN/A N/AN/A
Timeadd N secondsN/A N/AN/A

The '-' operation

Right operand
Left operandIntegerFloatDateTime
Integer-- (float)N/AN/A
Float- (float)+N/AN/A
Datesubtract N daysN/A N/AN/A
Timesubtract N secondsN/A - (int)*N/A

Notes and limitations

  • '(' and ')' can be used with any acceptable data type.
  • Logical values have only integer presentation. 1 for 'true' and '0' for 'false'.
  • Complex nested expressions like $$($$(8-2)-2) are not acceptable, use '()' instead of: $$((8-2)-2)
  • You should use @'name' column reference format in expressions. @number format is not supported for some kind of expressions.
  • * - approximate number of days between two dates.