What do the below SQL statements mean? Explain each query in a few steps.ALTER TABLE LINEITEMS

MODIFY Quantity CHECK $($Quantity $>0)$;

$$ Makoto Nakayama, Ph$.$D$.2/4$

o SELECT ORDERS.salesman$\_$id$,$ EMPLOYEES.last$\_$name,

EMPLOYEES.first$\_$name FROM ORDERS

INNER JOIN EMPLOYEES

ON EMPLOYEES.employee$\_$id$=$ORDERS.salesman$\_$id;

o SELECT $*$ FROM ORDERS

WHERE EXTRACT$($year FROM order$\_$date$)=2017$;