Step $4$ of Your PDA $($Personal Database Application$)$ In this PDA you shall write and run some SQL queries. If you wish, you may follow the routine of loading your database from your load file, running queries or other commands from a file that contains those SQL statements and then deleting your data so it doesn't clutter up the database all week and $($worse$)$ you don't forget and load the same tuples several times into your relations. Remember that SQL thinks of relations as bags, and so will happily let you insert the same tuple as many times as you ask it to$.$ To clean out a relation R without deleting the schema itself, use command DELETE FROM R; $(3\mathrm{.}5$ pts$.)$ Write three queries on your PDA database, using the select$-$from$-$where construct of SQL$.$ To receive full credit, all but perhaps one of your queries should exhibit some interesting feature of SQL: queries over more than one relation, or sub queries, for example. We suggest that you experiment with your SQL commands on a small database $($e$.$g$.,$ your hand$-$created database$),$ before running them on the large database that you loaded in PDA step $3.$ Initial debugging is much easier when you're operating on small amounts of data. Once you're confident that your queries are working, run them on your complete database. If you discover that most or all of your $``$interesting$\text{'}\text{'}$ queries return an empty answer on your large database, check whether you followed the instructions in step $3$ for generating data values that join properly. You will need to modify your data generator accordingly. Turn in a copy of all your SQL queries, along with a script illustrating their execution. $(3\mathrm{.}5$ pts$.)$ Write three data modification commands on your PDA database. Most of these commands should be $``$interesting$,\text{'}\text{'}$ in the sense that they involve some complex feature, such as inserting the result of a query, updating several tuples at once, or deleting a set of tuples that is more than one but less than all the tuples in a relation. As for the queries in $($a$),$ you might want to try out your commands on small data before trying it on your full database. Hand in a script that shows your modification commands running in a convincing fashion. $(3\mathrm{.}0$ pts$.)$ Create a report for part $($a$)$ using report facility of your DBMS software$($Oracle$,$ Access, MySQL$,$ etc.$)$