How to get user id to use in execute SQL statement?

Hi all,

I wanted to get the Current user ID & use it in SQL Statement and run the statement from workflow rule.

I am using #U on this statement: 

update Lead set Lead_AssignedUserID=#U where Lead_LeadID=#Lead_LeadID#

based on this reference: https://help.sagecrm.com/on_premise/en/2022R1/Administration/Content/Administrator/WC_Using__And_Symbols.htm?Highlight=%23U 

But it seems like it is not working.