Implicit relation tables always have `onDelete CASCADE`, this should be configurable.

Hi, currently you set the onDelete behaviour of generated associate tables in M:N relationships to CASCADE, e.g.:

CREATE TABLE "public"."_UserRoles" (
    "A" text NOT NULL,
    "B" text NOT NULL,
    CONSTRAINT "_UserRoles_A_fkey" FOREIGN KEY ("A") REFERENCES "public"."Role"("id") ON DELETE CASCADE,
    CONSTRAINT "_UserRoles_B_fkey" FOREIGN KEY ("B") REFERENCES "public"."User"("id") ON DELETE CASCADE
);

It would be great if we could configure it. I have a situation, when I would like to prohibit deletions of a Role if there exists an association to it through UserRole.

[janpio]

This has now been released as a preview feature behind a preview feature flag. You can read about it in the release notes for 2.26.0: https://github.com/prisma/prisma/releases/tag/2.26.0 If you have any feedback, please use this issue: https://github.com/prisma/prisma/issues/7816

[tomhoule]

This is the default the query engine (prisma client) relies on - the plan is to make this configurable, but it is pending on product work currently.