In Redis, it’s possible to set a key only if it doesn’t already exist. As with most things, there’s more than one way to do this.
Continue readingAuthor: Ian
How to Set an Expiry Only When the New Expiry is Greater Than the Existing Expiry in Redis
Redis 7.0.0 introduced some potentially useful options for setting timeouts on keys. One of these is the GT option, which allows us to set the expiry only if the new expiry is greater than the existing one.
The GT option is available for commands such as EXPIRE, EXPIREAT, PEXPIRE, and PEXPIREAT.
Redis SCARD Command Explained
In Redis, the SCARD command returns the number of members in the specified set. This is referred to as the cardinality of the set.
Redis SADD Command Explained
In Redis, the SADD command allows us to add members to a key. We can add multiple members if required.
A Redis set is an unordered collection of unique strings (members).
Continue readingHow to Get the First Day of the Month in SQL
Below are examples of using SQL to return the first day of the month across various DBMSs.
This could be the first day of the current month, or the first day of a month based on a given date.
Continue reading6 Ways to Set a String in Redis
When working with Redis, we have a number of options for setting keys that store string values.
Here are six ways to set a string value in Redis.
Continue reading2 Ways to Remove a Key’s Expiry in Redis
A Redis key can have an optional timeout, which makes the key expire after a certain amount of time, or at a certain time. We can use a couple of methods to remove any timeout associated with a key.
Here are two ways to remove a key’s expiry in Redis.
Continue readingHow to Update a Key and Return its Old Value in a Single Operation in Redis
When using the SET command to set a key in Redis, we can use the GET option to return its old value. This allows us to update the value of a key while returning the value that we’re replacing it with.
Note that this option was introduced in Redis 7.0.0, so if it doesn’t work, check your Redis version. If using an earlier version, try the GETSET command instead (which is deprecated from Redis version 6.2.0).
Subtract Months from a Date in SQLite
In SQLite, we can use the DATE() function to subtract one or more months from a date.
For datetime values, we can use the DATETIME() function.
Redis OBJECT IDLETIME Command Explained
In Redis, we can use the OBECT IDLETIME command to check how many seconds has passed since the last access to a given key.