SELECT sys.ps_thread_account(NULL); sys.ps_thread_account(NULL) NULL SELECT sys.ps_thread_account(234623462376); sys.ps_thread_account(234623462376) NULL SELECT sys.ps_thread_account(-1); ERROR 22003: Out of range value for column 'in_thread_id' at row 1 SELECT sys.ps_thread_account(sys.ps_thread_id(NULL)); sys.ps_thread_account(sys.ps_thread_id(NULL)) root@localhost Warnings: Note 1585 This function 'ps_thread_id' has the same name as a native function