T1 join T2 on T1.a = T2.a and T1.b = T2.b and T1.c = nvl(T2.c, T1.c)
Is the GitHub integration an additional fee on top of licenses for CA itself? I see a note at the bottom of the product's main page (https://www.ibm.com/support/pages/cognos-toolkit-github-integration) that says, "Cognos GitHub Integration is pre-packaged solution provided as a paid subscription. . . ."