Suppose that we have a ternary relationship R between entity set A, B and C such that A has a key constraint and a total participation and B has a key constraint; These are the only constraints. A has atributes a1 and a2, with a1 being the key; B and C are similatr. R has no descriptive attributes. Write DDL Statements that create relations corresponding to this information so as to capture as many of the constraints as possible. And if you can not capture some explain why?