Purpose
The purpose of this blog post is to explain the about the different Access Request tables and how these tables can be utilized in order to prepare reports as per your requirements:
1. Request Reason
Request reason is stored in SAPscript, with Text Object as "GRC" and ID as "LTXT". You can use standard SAPscript Function Module (READ_TEXT) to fetch request reason of a GRC request by passing the "TEXT" value to the Name field. This TEXT value can be fetched from table STXH
e.g: ACCREQ/00155D08DA361ED2A1BD201C710165A5/LONG_TEXT (For access requests ACCREQ/RequestID(GRACREQ Table)/LONG_TEXT
2. Request Comments
Request comments also are stored in SAPscript, with Text Object as "GRC" and ID as "NOTE". You can use standard SAPscript Function Module (READ_TEXT) to fetch comments of a GRC request by passing the "TEXT" value to the Name field in the same way as done above for request reason. This TEXT value can be fetched from table STXH.
e.g: ACCREQ/00155D08C4051ED4BDFDEF53EC12C0D7/20150511151344 (ACCREQ/RequestID(GRACREQ Table)/XXXX)
3. GRACREQ - Request details table
This table will provide the information about Request ID, Request Type, Request Creation Date and Request Priority
4. GRACREQUSER - GRC Request User details table
This table will provide the information about user for whom GRC request has been raised and provides details about User ID, User First Name, User Last Name and User Email ID
5. GRACREQPROVITEM - GRC Request Line Item Details
This table will provide the information about the request and the below Line Items in the request with their corresponding VALID FROM and VALID TO dates.
Role
System
Fire Fighter Id
User
Profile
PD Profile
FireFighter Role
6. GRACREQPROVLOG - GRC Request Provisioning Logs
This table will provide the information about the request and the Line Items in the request with their provisioning status (Success or Failure or Warning)
7. GRFNMWRTINST - GRC Request Instance Details
This table will provide the information about the request and its corresponding instance status.
8. GRFNMWRTDATLG - GRC Request Approval Status
Get the details of Instance ID from GRFNMWRTINST table by passing the request number in "EXTERNAL_KEY_DIS" field. Based on the Instance ID you can get the details of each Line Item approval status in the request, Path ID, Stage Sequence Number and Approver User column in this table gives the details of the approvers.
Based on Path ID you can get the stage details by using the tables "GRFNMWCNPATH" and "GRFNMWCNSTG"
9. GRACROLE & GRACROLEAPPRVR
These tables will provide the information about the roles and their corresponding role owners maintained in BRM.
10. HRUS_D2 - Approver Delegation Table
This table will provide the information about the delegated approvers in GRC
11. GRACSTDROLE and GRACSTDROLESYS
These tables will provide the information about the default roles maintained in GRC.
Looking forward for all your inputs in improving this blog by including additional table details (if any missing) 
Thanks for reading.
Best Regards,
Madhu Babu Sai