SESSION_ID (Transact-SQL)
Applies to: 
Azure Synapse Analytics
Analytics Platform System (PDW)
Returns the ID of the current Azure Synapse Analytics or Analytics Platform System (PDW) session.
Transact-SQL syntax conventions
Syntax
-- Azure Synapse Analytics and Parallel Data Warehouse
SESSION_ID ( )
Return Value
Returns an nvarchar(32) value.
General Remarks
The session ID is assigned to each user connection when the connection is made. It persists for the duration of the connection. When the connection ends, the session ID is released.
The session ID begins with the alphabetical characters 'SID'. These are case-sensitive and must be capitalized when session ID is used in SQL commands.
You can query the view sys.dm_pdw_exec_sessions to retrieve the same information as this function.
Examples
The following example returns the current session ID.
SELECT SESSION_ID();