Date_diff function in LookML

[Punita]

Hi,
Can you help me understand why I am getting an error with the below date_diff expression in ML? I want to get the days between the date (in the grouped dimension) and today’s date.

dimension: date_diff {
type: number
sql: DATEDIFF(day, ${date_joined_date}, GETDATE()) ;;
}

Thank you!