Q$\mathrm{.}3($a$)$ Why Concurrency control is required in DBMS$?$ Discuss with examples $($b$)$ Consider the following schedules

S : rl $($A$)$ ; r$2($A$)$ ; rl $($B$)$ ; r$2($B$)$ ; r$3($B$)$ ; wl $($A$)$; w$2($B$)$ Check whether the given schedule is conflict serializable or not and explain why?

$($c$)$ What is two phase locking $(2$PL$)$ protocol? How does $2$PL ensures conflict

serializability? Explain with appropriate example.$$