ZRANGEBYSCORE for score-based queries in Redis - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to get all members with scores between 10 and 20.

Redis

ZRANGEBYSCORE mysortedset [1] 20

Drag options to blanks, or click blank then click option'

A10

B5

C30

D-inf

Attempts:

3 left

💡 Hint

Common Mistakes

Using a score lower than 10 will include unwanted members.

Using a string instead of a number for the score.

The command ZRANGEBYSCORE mysortedset 10 20 returns all members with scores from 10 to 20 inclusive.

2fill in blank

medium

Complete the code to get members with scores greater than or equal to 15.

Redis

ZRANGEBYSCORE mysortedset [1] +inf

Drag options to blanks, or click blank then click option'

A15

B(15

C-inf

D20

Attempts:

3 left

💡 Hint

Common Mistakes

Using (15 excludes score 15 itself.

Using -inf will include all scores.

Using ZRANGEBYSCORE mysortedset 15 +inf returns members with scores 15 and above.

3fill in blank

hard

Fix the error in the code to exclude members with score 10 but include scores above 10.

Redis

ZRANGEBYSCORE mysortedset [1] 20

Drag options to blanks, or click blank then click option'

A[10

B10

C(10

D-inf

Attempts:

3 left

💡 Hint

Common Mistakes

Using 10 includes score 10.

Using [10 is invalid syntax.

Using (10 excludes score 10 but includes scores greater than 10.

4fill in blank

hard

Fill both blanks to get members with scores strictly between 5 and 15.

Redis

ZRANGEBYSCORE mysortedset [1] [2]

Drag options to blanks, or click blank then click option'

A(5

B5

C(15

D15

Attempts:

3 left

💡 Hint

Common Mistakes

Using 5 or 15 includes those scores.

Using brackets [ ] is invalid in Redis score ranges.

Using (5 and (15 excludes scores 5 and 15, returning members strictly between those scores.

5fill in blank

hard

Fill all three blanks to get members with scores from 0 (inclusive) to 100 (exclusive), limiting to 10 results starting from the second member (offset 1).

Redis

ZRANGEBYSCORE mysortedset [1] [2] LIMIT [3] 10

Drag options to blanks, or click blank then click option'

A0

B100

C(100

D1

Attempts:

3 left

💡 Hint

Common Mistakes

Using 100 includes score 100.

Using LIMIT 0 10 starts from first member, not second.

Using 0 as offset starts from the first member.

The command ZRANGEBYSCORE mysortedset 0 (100 LIMIT 1 10 returns members with scores from 0 inclusive to less than 100, starting from the second member (offset 1), limiting to 10 results.

Practice

1. What does the Redis command ZRANGEBYSCORE do?

easy

A. It returns the rank of a member in a sorted set.

B. It deletes members from a sorted set by score.

C. It adds a member with a score to a sorted set.

D. It returns members in a sorted set within a given score range.

Solution

1. Step 1: Understand the command purpose

   ZRANGEBYSCORE is used to get members from a sorted set based on their scores.

2. Step 2: Compare options with command behavior

   Only It returns members in a sorted set within a given score range. correctly describes returning members within a score range.

3. Final Answer:

   It returns members in a sorted set within a given score range. -> Option D

4. Quick Check:

   ZRANGEBYSCORE = returns members by score range [OK]

Hint: ZRANGEBYSCORE fetches by score range, not by rank or deletion [OK]

Common Mistakes:

• Confusing ZRANGEBYSCORE with ZREM (deletion)
• Thinking it returns rank instead of members
• Mixing it up with ZADD (adding members)

2. Which of the following is the correct syntax to get members with scores between 10 and 20 from sorted set myzset including their scores?

easy

A. ZRANGEBYSCORE myzset 10 20 INCLSCORES

B. ZRANGEBYSCORE myzset 10 20 WITHSCORE

C. ZRANGEBYSCORE myzset 10 20 WITHSCORES

D. ZRANGEBYSCORE myzset 10 20 SCORES

Solution

1. Step 1: Recall correct option for including scores

   The correct keyword to include scores in output is WITHSCORES.

2. Step 2: Check syntax correctness

   ZRANGEBYSCORE myzset 10 20 WITHSCORES uses the exact correct syntax: ZRANGEBYSCORE myzset 10 20 WITHSCORES.

3. Final Answer:

   ZRANGEBYSCORE myzset 10 20 WITHSCORES -> Option C

4. Quick Check:

   WITHSCORES keyword includes scores [OK]

Hint: Use WITHSCORES exactly to get scores with members [OK]

Common Mistakes:

• Misspelling WITHSCORES
• Using WITHSCORE or SCORES instead
• Omitting WITHSCORES when scores are needed

3. Given the sorted set myzset with members and scores:
"a"=5, "b"=10, "c"=15, "d"=20, "e"=25
What is the result of ZRANGEBYSCORE myzset 10 20 LIMIT 1 2?

medium

A. ["c", "d"]

B. ["b", "c", "d"]

C. ["b", "c"]

D. ["a", "b"]

Solution

1. Step 1: Identify members in score range 10 to 20

   Members with scores 10, 15, 20 are "b", "c", "d".

2. Step 2: Apply LIMIT 1 2

   LIMIT 1 2 means skip 1 member, then return next 2 members. Skipping "b", next two are "c", "d".

3. Final Answer:

   ["c", "d"] -> Option A

4. Quick Check:

   LIMIT skips then returns count [OK]

Hint: LIMIT offset count skips offset, returns count members [OK]

Common Mistakes:

• Ignoring LIMIT offset and returning from start
• Confusing score range with member count
• Including members outside score range

4. You run the command ZRANGEBYSCORE myzset (10 20 but get an error. What is the likely cause?

medium

A. Syntax error due to missing closing parenthesis after 20.

B. Incorrect use of parentheses for exclusive range; missing closing parenthesis.

C. Command is missing the key name.

D. Missing closing parenthesis for exclusive range syntax.

Solution

1. Step 1: Analyze the command syntax

   The command uses (10 to indicate exclusive minimum score 10, which is correct syntax.

2. Step 2: Identify the error

   The command ends with 20 without closing parenthesis or space, causing syntax error.

3. Final Answer:

   Syntax error due to missing closing parenthesis after 20. -> Option A

4. Quick Check:

   Exclusive range needs parentheses on score values [OK]

Hint: Check parentheses carefully for exclusive score ranges [OK]

Common Mistakes:

• Forgetting parentheses for exclusive ranges
• Missing spaces between arguments
• Using parentheses incorrectly around scores

5. You want to get the top 3 members with scores between 0 and 100 from sorted set myzset, including their scores, but only if their score is greater than 50. Which command achieves this?

hard

A. ZRANGEBYSCORE myzset 50 100 WITHSCORES LIMIT 0 3

B. ZRANGEBYSCORE myzset (50 100 WITHSCORES LIMIT 0 3

C. ZRANGEBYSCORE myzset [50 100 WITHSCORES LIMIT 0 3

D. ZRANGEBYSCORE myzset (50 100 LIMIT 3 WITHSCORES

Solution

1. Step 1: Define score range with exclusive lower bound

   To get scores greater than 50, use (50 for exclusive minimum.

2. Step 2: Include scores and limit results

   Use WITHSCORES to include scores and LIMIT 0 3 to get top 3 members.

3. Step 3: Verify command syntax

   ZRANGEBYSCORE myzset (50 100 WITHSCORES LIMIT 0 3 correctly uses ZRANGEBYSCORE myzset (50 100 WITHSCORES LIMIT 0 3.

4. Final Answer:

   ZRANGEBYSCORE myzset (50 100 WITHSCORES LIMIT 0 3 -> Option B

5. Quick Check:

   Exclusive range + WITHSCORES + LIMIT = correct command [OK]

Hint: Use (score for exclusive, WITHSCORES, then LIMIT offset count [OK]

Common Mistakes:

• Using inclusive 50 instead of exclusive
• Placing LIMIT before WITHSCORES
• Using wrong bracket types for exclusive range