In the world of database management systems (DBMSs) and computer programming, CRUD is an acronym that stands for Create, Read, Update, and Delete. These are considered to be the four basic operations of persistent storage.
Let’s take a look at how CRUD fits into database management systems and programming in general.
Continue readingIf you get an error that reads “WRONGTYPE Operation against a key holding the wrong kind of value” when using the ZPOPMIN or ZPOPMAX commands in Redis, it’s because you’re passing a key with the wrong data type.
The same issue can apply when using the blocking variants of these commands (BZPOPMIN and BZPOPMAX).
To fix this issue, make sure you pass a sorted set to these commands.
Continue readingIf you’re getting an error that reads “ERR wrong number of arguments for ‘hstrlen’ command“, it’s because you’re passing the wrong number of arguments when using the HSTRLEN command.
The HSTRLEN command requires two arguments (at the time of writing). These are the name of the key and the name of the field.
If you’re getting this error, check the number of arguments that you’re passing and adjust if required.
Continue readingIf you get an error that reads “WRONGTYPE Operation against a key holding the wrong kind of value” when using the ZSCORE command in Redis, it’s because you’re passing a key with the wrong data type.
To fix this issue, make sure that you pass a sorted set to the ZSCORE command.
If you’re getting an error that reads “ERR wrong number of arguments for ‘hrandfield’ command“, it’s probably because you’re not passing any arguments when using the HRANDFIELD command.
The HRANDFIELD command requires at least one argument, and accepts up to three arguments (at the time of writing).
If you get an error that reads “WRONGTYPE Operation against a key holding the wrong kind of value” when setting a hash with a command like HSET or HSETNX, it’s probably because you’re trying to set a non-hash key that already exists. In other words, the key already exists, but it doesn’t contain a hash.
To fix this issue, be sure to use these commands on keys that either don’t already exist, or contain a hash.
Continue readingIn Redis, the ZRANGESTORE command works just like the ZRANGE command except that it stores the result in a key.
Basically, it allows us to get all members from a sorted set between a certain range and store them in a new key.
Continue readingIf you’re getting an error that reads “ERR wrong number of arguments for ‘srandmember’ command” in Redis, it’s probably because you’re calling the SRANDMEMBER command without any arguments.
To fix this issue, make sure you pass the correct number of arguments. At the time of writing, the SRANDMEMBER command requires at least one argument, and accepts an optional second argument.
In Redis, the ZMSCORE command allows us to get the score of one or members in a sorted set.
If you get an error that reads “WRONGTYPE Operation against a key holding the wrong kind of value” when using the ZINTER command in Redis, it’s probably because you’re passing a key with the wrong data type.
To fix this issue, be sure that each key you pass to the ZINTER command is either a set or a sorted set.