SET and GET commands in Redis - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to set the key "name" with the value "Alice" in Redis.

Redis

SET name [1]

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

Avalue

B"Alice"

Cname

DAlice

Attempts:

3 left

💡 Hint

Common Mistakes

Quoting the string value unnecessarily

Using the key name as the value

The SET command stores the value as a string, but you do not need to quote the value in the Redis CLI; quotes are used in some programming languages but not in Redis commands.

2fill in blank

medium

Complete the code to get the value of the key "name" from Redis.

Redis

[1] name

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

ASET

BDEL

CGET

DEXPIRE

Attempts:

3 left

💡 Hint

Common Mistakes

Using SET instead of GET

Using DEL which deletes keys

The GET command retrieves the value stored at the given key.

3fill in blank

hard

Fix the error in the command to set the key "age" to 30 in Redis.

Redis

SET age [1]

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

A30

Bthirty

Cage

D"30"

Attempts:

3 left

💡 Hint

Common Mistakes

Quoting numeric values unnecessarily

Using the key name as the value

Redis stores values as strings, but numeric values can be set without quotes in Redis CLI.

4fill in blank

hard

Fill both blanks to set the key "city" to "Paris" and then get its value.

Redis

SET city [1]
[2] city

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

A"Paris"

BGET

CSET

Dcity

Attempts:

3 left

💡 Hint

Common Mistakes

Quoting the value unnecessarily in SET

Using SET instead of GET to retrieve

First, set the key with the value. Then use GET to retrieve it.

5fill in blank

hard

Fill all three blanks to set the key "language" to "Redis", get it, and then delete it.

Redis

SET language [1]
[2] language
[3] language

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

A"Redis"

BGET

CDEL

DSET

Attempts:

3 left

💡 Hint

Common Mistakes

Quoting the value unnecessarily in SET

Using SET instead of GET or DEL

Forgetting to delete the key

Set the key with the value, get it with GET, then delete it with DEL.

Practice

1. What does the Redis SET command do?

easy

A. Retrieves a value by key

B. Stores a value with a specified key

C. Deletes a key and its value

D. Lists all keys in the database

Solution

1. Step 1: Understand the purpose of SET

   The SET command in Redis is used to save or store a value associated with a key.

2. Step 2: Compare with other commands

   GET retrieves values, DEL deletes keys, and KEYS lists keys, so they are not correct here.

3. Final Answer:

   Stores a value with a specified key -> Option B

4. Quick Check:

   SET saves data = A [OK]

Hint: SET saves data by key, GET fetches it [OK]

Common Mistakes:

• Confusing SET with GET
• Thinking SET deletes data
• Mixing SET with key listing

2. Which of the following is the correct syntax to store the value "hello" with the key "greeting" in Redis?

easy

A. SET greeting hello

B. GET greeting hello

C. SET "greeting" "hello"

D. SET greeting, hello

Solution

1. Step 1: Recall Redis SET syntax

   The correct syntax is SET key value without commas or quotes unless the shell requires them.

2. Step 2: Analyze options

   SET greeting hello matches the correct syntax. GET greeting hello uses GET which is wrong. SET "greeting" "hello" uses quotes unnecessarily. SET greeting, hello uses a comma which is invalid.

3. Final Answer:

   SET greeting hello -> Option A

4. Quick Check:

   SET key value no commas [OK]

Hint: Use SET key value without commas or quotes [OK]

Common Mistakes:

• Using GET instead of SET
• Adding commas between arguments
• Unnecessary quotes around key/value

3. Given the following Redis commands executed in order:

SET color blue
GET color
SET color red
GET color

What will be the output of the two GET commands?

medium

A. "blue" and then "red"

B. "red" and then "blue"

C. "blue" and then "blue"

D. nil and then "red"

Solution

1. Step 1: Analyze the first SET and GET

   The first SET color blue stores "blue". The first GET color returns "blue".

2. Step 2: Analyze the second SET and GET

   The second SET color red overwrites the value with "red". The second GET color returns "red".

3. Final Answer:

   "blue" and then "red" -> Option A

4. Quick Check:

   SET overwrites value, GET returns current value [OK]

Hint: SET overwrites; GET returns latest value [OK]

Common Mistakes:

• Assuming GET returns old value
• Thinking SET appends values
• Expecting nil on first GET

4. You run the command GET username but get a nil response. Which of the following could fix this issue?

medium

A. Run GET username again immediately

B. Use DEL username before GET

C. Restart the Redis server

D. Run SET username "guest" before GET

Solution

1. Step 1: Understand nil response from GET

   Nil means the key "username" does not exist or has no value stored.

2. Step 2: Fix by setting a value

   To get a value, you must first store it using SET username "guest". Other options do not create the key.

3. Final Answer:

   Run SET username "guest" before GET -> Option D

4. Quick Check:

   Nil means no key; SET creates it [OK]

Hint: Nil means missing key; SET it first [OK]

Common Mistakes:

• Retrying GET without SET
• Deleting key before GET
• Restarting server unnecessarily

5. You want to store a user's session token in Redis with key "session:123" and value "abc123token". Which sequence of commands correctly stores and retrieves this token?

hard

A. SET session:123 abc123token
DEL session:123
GET session:123

B. GET session:123
SET session:123 abc123token

C. SET session:123 abc123token
GET session:123

D. SET "session:123" "abc123token"
DEL session:123
GET session:123

Solution

1. Step 1: Store the session token

   Use SET session:123 abc123token to save the token under the key.

2. Step 2: Retrieve the stored token

   Use GET session:123 to fetch the token value.

3. Step 3: Analyze other options

   GET session:123 SET session:123 abc123token tries to GET before SET, so returns nil. Options A and C delete the key before GET, so GET returns nil.

4. Final Answer:

   SET session:123 abc123token GET session:123 -> Option C

5. Quick Check:

   SET then GET returns stored value [OK]

Hint: Always SET before GET to retrieve stored data [OK]

Common Mistakes:

• GET before SET returns nil
• Deleting key before GET
• Using quotes unnecessarily