If we need to add a virtual column to an existing table in Oracle Database, we can do so with the usual SQL ALTER TABLE statement.
how to
Fix “ERR wrong number of arguments for ‘sintercard’ command” in Redis
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.
Subtract Seconds from a Time Value in PostgreSQL
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.
5 Ways to See if a Table has a Generated Column in MySQL
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.
How to Return the Expiry Time as a Unix Timestamp in Redis
In 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.
2 Ways to Set a Redis Key Only When it Doesn’t Already Exist
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.