Write MySQL$,$ PL$/$SQL$,$ or T$-$SQL procedures to accomplish the following task:

a$.$ Obtain the name and credit limit of the customer whose ID is currently stored in I$\_$CUST$\_$ID$.$ Place these values in the variables I$\_$CUSTOMER$\_$NAME and I$\_$CREDIT$\_$LIMIT, respectively. Output the contents of I$\_$CUSTOMER$\_$NAME and I$\_$CREDIT$\_$LIMIT.

b$.$ Obtain the invoice date, customer ID$,$ and first and last names for the invoice whose number currently is stored in I$\_$INVOICE$\_$NUM. Place these values in the variables I$\_$INVOICE$\_$DATE, I$\_$CUST$\_$ID$,$ and I$\_$CUST$\_$NAME, respectively. Output the contents of I$\_$INVOICE$\_$DATE, I$\_$CUST$\_$ID$,$ and I$\_$CUST$\_$NAME.

c$.$ Add a row to the INVOICE table.

d$.$ Change the date of the invoice whose number is stored in I$\_$INVOICE$\_$NUM to the date currently found in I$\_$INVOICE$\_$DATE.

e$.$ Delete the invoice whose number is stored in I$\_$INVOICE$\_$NUM.