The SID of the SAP System defined in the Connection object is in the column OCV_VName of the table OCV. If the SID of the Connection object VMSAP is needed, please use the query below.
select OCV_Value from OCV where OCV_VName='rfcSystem_name' and OCV_OH_Idnr IN (select OH_Idnr from OH where OH_Name='VMSAP ')