Do you want only Test Instances that have linked defects, or do you want all Test Instances?
The following give just the Test Instances that have linked defects.
SELECT TESTCYCL.TC_TESTCYCL_ID /*Test Instance.Test Instance Unique ID*/, TEST.TS_NAME /*Test.Test Name*/, TESTCYCL.TC_STATUS /*Test Instance.Status*/, link.ln_bug_id, BUG.BG_STATUS /*Defect.Status*/, BUG.BG_SUMMARY /*Defect.Summary*/ FROM TESTCYCL, TEST, LINK, BUG WHERE TEST.TS_TEST_ID = TESTCYCL.TC_TEST_ID and LINK.LN_ENTITY_TYPE = 'TESTCYCL' and link.LN_ENTITY_ID = TESTCYCL.TC_TESTCYCL_ID and bug.bg_bug_id = link.ln_bug_id