SISMEMBER for membership check in Redis - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the Redis command SISMEMBER do?

It checks if a given element is a member of a specified set and returns 1 if true, 0 if false.

beginner

How do you use SISMEMBER to check if 'apple' is in the set 'fruits'?

Use the command: SISMEMBER fruits apple. It returns 1 if 'apple' is in 'fruits', otherwise 0.

beginner

What type of data structure does SISMEMBER work with in Redis?

SISMEMBER works only with sets, which are unordered collections of unique elements.

beginner

What is the return value of SISMEMBER if the element is not found in the set?

It returns 0, indicating the element is not a member of the set.

intermediate

Can SISMEMBER be used on Redis data types other than sets?

No, SISMEMBER only works with sets. Using it on other types will cause an error.

What does the Redis command SISMEMBER myset value return if 'value' is in 'myset'?

A 0

B The value itself

C An error

D 1

SISMEMBER returns 1 if the element is a member of the set.

Which Redis data type is required for SISMEMBER to work?

A Set

B Hash

C String

D List

SISMEMBER only works with sets.

What does SISMEMBER return if the element is not in the set?

A Null

B 1

C 0

D An error

It returns 0 to indicate the element is not a member.

If you run SISMEMBER on a key that does not exist, what is the result?

A 0

B An error

C 1

D Null

If the set does not exist, Redis treats it as empty and returns 0.

Which of the following commands checks membership in a Redis set?

A GET

B SISMEMBER

C HGET

D LPUSH

SISMEMBER is the command to check membership in a set.

Explain how the Redis command SISMEMBER works and what it returns.

Think about checking if an item is in a group.

Describe a real-life example where you might use SISMEMBER in Redis.

Imagine checking if a friend is in your contact list.