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7. A natural join in a relational database takes two tables of information and combines entries from the tables that share a particular field. You can read more about this at Wikipedia. Interpret the tables below as sets of sets? For the Course Enrollment Table define A = {{A38182818, Spring2021, Math230,01},..., {A56363631, Spring2021, Math454,01}}, and for the Student Table define B = {{Al, A81723653}, {Jo, A38182818}, {Su, A56363631}}. Course Enrollment Table A38182818 Spring 2021 Math23001 Student Table A81723653 Spring2021 Math350 01 Al A81723653 A81723653 Fall2020 Math152 04 Jo A56363631 A38182818 Fall2020 Math332 02 Su A38182818 A56363631 Spring2021 Math454 01 (a) Construct the set C = {x Uy : x A, Y E B, xny#0}. (b) Represent the resulting set C from part (a) as a table, similar to what you see above. Make sure to write down the table for C in a reasonably sorted order. (c) Why would you want to query the database for the set {x EC: Al E x}? Be specific. (This corresponds to a "SELECT statement from the JOIN of two tables in database query language.)