A Test Instance is a special record linking a Test Case from the Test Plan to a Test Set in the Test Lab.
When you run a Test Instance that spawns a new record - a Run record, which summarized information about that execution of that Test Instance.
In the Manual Runner when you then click Begin Run, in real time the application follows the link from the Run back to the Test Instance to find the source Test Case. It then follows the link from the Test Case to the Design Steps records to find the steps for the test case. It then makes a copy of each Design Step in the STEPS table (executed Design Steps). STEPS are linked to a Run record. STEPS don't exist until a Test Instance has been Run.
You may want to study the Database Reference documentation to better understand the relationships between the entities.
Accessing the data from QTP depends on the context. Is QTP trying to obtain this info for a Test it is current running, or for a test that has already been run? In either case, you will use the QCUtil object in QTP to connect to QC to get at the data. The QCUtil object gives you access to the entire Open Test Architecture API for QC. Through that you can get to pretty much all the data in a project. There's a reference document in the QC application for the API also that you'll probably need to study.
When you run a Test Instance that spawns a new record - a Run record, which summarized information about that execution of that Test Instance.
In the Manual Runner when you then click Begin Run, in real time the application follows the link from the Run back to the Test Instance to find the source Test Case. It then follows the link from the Test Case to the Design Steps records to find the steps for the test case. It then makes a copy of each Design Step in the STEPS table (executed Design Steps). STEPS are linked to a Run record. STEPS don't exist until a Test Instance has been Run.
You may want to study the Database Reference documentation to better understand the relationships between the entities.
Accessing the data from QTP depends on the context. Is QTP trying to obtain this info for a Test it is current running, or for a test that has already been run? In either case, you will use the QCUtil object in QTP to connect to QC to get at the data. The QCUtil object gives you access to the entire Open Test Architecture API for QC. Through that you can get to pretty much all the data in a project. There's a reference document in the QC application for the API also that you'll probably need to study.