$1.$Create a program script that uses a PL$/$SQL anonymous block to perform the following:Use a host variable AREA to store the result. Declare a local variable RADIUS with numeric data type. Declare a constant PI with value $3\mathrm{.}14.$ Assign a value to the variable RADIUS by using a substitution variable. Calculate area of a circle by using formulaAREA $=$ PI $*$ RADIUS $*$ RADIUSThen print result in SQL$*$Plus$\mathrm{.}2.$Write a PL$/$SQL block to find the square, cube, and double of a number inputted with a substitution variable, and print results using built$-$in package DBMS$\_$OUTPUT$\mathrm{.}3.$Write a PL$/$SQL block to swap the values of two variables. Print variables before and after swapping$\mathrm{.}4.$Write a PL$/$SQL program to input hours and rate. Find gross pay and net pay. The tax rate is $28\%.$ Print your results$\mathrm{.}5.$Write a PL$/$SQL program with two variables for the first name and the last name. Print the full name with last name and first name separated by comma and a space$\mathrm{.}6.($OPTIONAL$)$ Write a PL$/$SQL program to retrieve the full name of a given employee id$.$ Print the full name with last name and first name seperated by comma and a space.