Redis ZSET Data type

redis-zset.rb

127.0.0.1:6379> ZADD class1:math 98 Tithi 50 Raju 80 Andrew # Create a new class 1 math score SET. 
(integer) 3                                                 # Add three members with their respective scores
127.0.0.1:6379> ZRANGEBYSCORE class1:math 0 10   # Fetch students scored between 0 to 10. No Student scored between 0 to 10
(empty list or set)
127.0.0.1:6379> ZRANGEBYSCORE class1:math 0 60  # Fetch students scored between 0 to 60. Raju
1) "Raju"
127.0.0.1:6379> ZRANGEBYSCORE class1:math 0 60  WITHSCORES # Fetch students with scores who scored between 0 to 60. Raju
1) "Raju"
2) "50"
127.0.0.1:6379> ZRANGE class1:math 0 10  WITHSCORES # Fetch students from ZSET class1:math with position 0 to 10. 
1) "Raju"                                           # Returns all students as only 3 students are added to ZSET class1:math
2) "50"
3) "Andrew"
4) "80"
5) "Tithi"
6) "98"
127.0.0.1:6379> ZRANGE class1:math 0 1  WITHSCORES # Fetch students from ZSET class1:math with position 0 to 1. 
1) "Andrew"                                        # Returns first 2 students from ZSET class1:math
2) "80"
3) "Tithi"
4) "98"
127.0.0.1:6379> ZRANGE class1:math 0 -1  WITHSCORES # Fetch ALL students from ZSET class1:math with position 0 to -1(end). 
1) "Raju"
2) "50"
3) "Andrew"
4) "80"
5) "Tithi"
6) "98"
127.0.0.1:6379> ZREM class1:math Arjun # REMOVE student Arjun from ZSET class1:math. Returns 0 as failure
(integer) 0
127.0.0.1:6379> ZRANGE class1:math 0 -1  WITHSCORES # Fetch ALL students from ZSET class1:math with position 0 to -1(end). Same list as earlier
1) "Raju"
2) "50"
3) "Andrew"
4) "80"
5) "Tithi"
6) "98"
127.0.0.1:6379> ZREM class1:math Raju # REMOVE student Raju from ZSET class1:math. Returns 1 as success
(integer) 1
127.0.0.1:6379> ZRANGE class1:math 0 -1  WITHSCORES # Fetch ALL students from ZSET class1:math with position 0 to -1(end). 
1) "Andrew"                                         # NOTE: Raju is not listed in complete list
2) "80"
3) "Tithi"
4) "98"