If you’re getting an error that reads “ERR wrong number of arguments for ‘sintercard’ command” in Redis, it’s because you’re calling the SINTERCARD command with the wrong number of arguments.
To fix this issue, make sure you’re passing the correct number of arguments.
Continue readingIn MariaDB, we can use the LOWER() function to convert uppercase characters to their lowercase equivalent.
We can alternatively use LCASE(), which is a synonym of LOWER().
When setting a timeout on a key in Redis, we have the option of setting the timeout only if it’s less than the existing timeout. We can do this with the LT option of commands such as EXPIRE, EXPIREAT, PEXPIRE, and PEXPIREAT.
In PostgreSQL, we can use the - operator to subtract one or more seconds from a time value.
By “time” value, this could be an actual time value, a timestamp, or an interval. We can also subtract seconds from a date value or a date and time combination.
In Redis, typically when we want to return a key’s value, we use the GET command. But there’s also a GETEX command (introduced in Redis 6.2.0) that allows us to get the value and return it’s expiry at the same time.
MySQL supports generated columns. If you’re not sure whether a table has a generated column or not, you can check it using any of the following methods.
Continue readingIn Redis, we have several options for returning the expiry time of a key. One option from Redis 7.0.0 and above is to return it as a Unix timestamp.
When returning the expiry as a Unix timestamp, we can have it returned in seconds or milliseconds. To return it in seconds, we can use the EXPIRETIME command. To return it in milliseconds, we can use the PEXPIRETIME command.
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 readingRedis 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.
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.
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