$subtract
Reference group: Arithmetic expressions
What it does
Subtracts values; subtracting dates returns elapsed milliseconds.
Syntax
{$subtract: [expr1, expr2]}
Use case
Margins and durations.
$subtract: practical example
{ $project: { margin: { $subtract: ["$revenue", "$cost"] } } }💡 Explanation
Subtracts values; subtracting dates returns elapsed milliseconds.
When to use it
Margins and durations.
Key Takeaways
- Subtracts values; subtracting dates returns elapsed milliseconds.
- Typical use: Margins and durations.