90 items
Decrementing a Counter with DECR
Code QuizDecrementing Numeric Strings
QuizSTRLEN Command
FlashcardAppending and Getting String Length
Slides / VideoChoosing the Right Redis Data Structure
Slides / VideoListing Keys with the KEYS Command
Slides / VideoWorking with Sorted Sets (ZADD and ZRANGE)
Slides / VideoSorted Set Data Type Basics
Slides / VideoWorking with Sets (SADD and SMEMBERS)
Slides / VideoSet Data Type Basics
Slides / VideoWorking with Hashes (HSET and HGET)
Slides / VideoHash Data Type Basics
Slides / VideoReading Sorted Set Ranges
QuizChoosing a Data Structure
QuizSorted Set Ranking
QuizSet Cardinality
QuizKey Naming Conventions
QuizChecking a Key's Type
QuizListing Keys by Pattern
QuizAdding Set Members
QuizIncrementing Numeric Strings
QuizGetting Hash Fields
QuizChecking Key Existence
QuizAppending to Strings
QuizSetting Multiple Keys
QuizReading List Ranges
QuizRedis List Structure
QuizList Length
QuizPushing to Lists
QuizSorted Set Score Ordering
QuizPopping from Lists
QuizHash Field-Value Structure
QuizAdding to Sorted Sets
QuizSet Uniqueness Property
QuizDeleting Keys
QuizDeleting Hash Fields
QuizChecking Set Membership
QuizReading and Popping Redis Lists
Slides / VideoAdding to Lists with LPUSH and RPUSH
Slides / VideoList Data Type Basics
Slides / VideoSetting Key Expiration with EXPIRE and TTL
Slides / VideoIncrementing and Decrementing with INCR/DECR
Slides / VideoDEL and EXISTS Commands for Keys
Slides / VideoSET and GET Basics
Code QuizExpiring a Key with SET EX
Code QuizFinding Keys by Pattern
Code QuizBuilding a FIFO Queue
Code QuizRange by Score
Code QuizIncrementing a Counter
Code QuizSet Difference Order
Code QuizAdding to a Sorted Set
Code QuizLooking Up a Score
Code QuizChecking Set Membership
Code QuizMeasuring List Length
Code QuizRemoving a Hash Field
Code QuizPersisting an Expiring Key
Code QuizGetting the First Three Items
Code QuizChoosing the Right Structure
Code QuizDeleting and Checking Keys
Code QuizRemoving a Set Member
Code QuizReading a Hash Field
Code QuizSET and GET Commands for Strings
Slides / VideoINCR and DECR Commands
FlashcardTYPE Command
FlashcardSET and GET Commands
FlashcardRedis Sorted Set Data Type
FlashcardLPOP and RPOP Commands
FlashcardFLUSHDB and FLUSHALL Commands
FlashcardLPUSH and RPUSH Commands
FlashcardLRANGE Command
FlashcardRedis Hash Data Type
FlashcardRedis List Data Type
FlashcardRedis Set Data Type
FlashcardHDEL and HEXISTS Commands
FlashcardZADD Command
FlashcardSMEMBERS and SISMEMBER Commands
FlashcardDEL Command
FlashcardAPPEND and String Manipulation
FlashcardSCARD Command
FlashcardHSET and HGET Commands
FlashcardSADD and SREM Commands
FlashcardKEYS Command
FlashcardLLEN Command
FlashcardZRANK and ZSCORE Commands
FlashcardEXISTS Command
FlashcardRedis String Data Type
FlashcardZRANGE and ZRANGEBYSCORE
FlashcardRENAME Command
FlashcardHGETALL Command
FlashcardChoosing the Right Data Structure
FlashcardDecrementing a Counter with DECR
Spot the bug in code that tries to decrease a Redis counter by a specific amount.
// stock starts at 10
await client.set('stock', 10);
// a customer buys 3 items
await client.decr('stock', 3);
const remaining = await client.get('stock');
console.log(remaining); // expected 7What is the bug in this code?