In Redis, the RENAMENX command renames a key, but only if the new key doesn’t already exist.
RENAMENX is similar to the RENAME command, except that it only renames the key if the new one doesn’t already exist. The RENAME command on the other hand, will overwrite the new key if it already exists.
The Redis CLI allows us to easily run a command multiple times. All we need to do is prefix the command with the number of times we want it to run.
Continue readingIn Redis, the RENAME command renames a key. It allows us to give a key a new name.
If you ever need to use SQL to return just the numeric values in a character column, the method you use will largely depend on your DBMS. Most DBMSs support regular expressions (regex), but some don’t. And some include functions that can detect numeric values.
Here are examples of how to do it in the more popular DBMSs.
Continue readingIn Redis, the COPY command copies the value from one key to another.
This command was introduced in Redis 6.2.0.
Continue readingIn Redis, the RESTORE command creates a key associated with a value that is obtained by deserialising the provided serialised value (obtained via the DUMP command).
The serialisation format contains a 64-bit checksum, as well as the RDB version. The RESTORE command checks the RDB version and data checksum. If they don’t match an error is returned.
In Redis, the GETRANGE command allows us to get part of a string at a given key, starting and ending at the specified offsets.
The GETRANGE command replaced the SUBSTR command, which basically does the same thing. The SUBSTR command is now considered deprecated (as of Redis 2.0.0).
In Redis, the SETRANGE command allows us to overwrite part of a string at a given key, starting at a specified offset. It overwrites the old value from the specified offset, for the entire length of the new value.
In MariaDB, the CASE statement can be used in stored programs to perform a complex conditional construct. It compares a list of conditions and returns a different result depending on which condition (if any) is matched.
The CASE statement is distinct from the CASE operator, in that the CASE statement is specifically for use in stored programs. Also, there’s a slight difference in the syntax.
In Redis, the DECRBY command decrements the value of a key by the specified amount.
If the key doesn’t exist, DECRBY creates the key with a value of 0 and then decrements it by the specified amount.
An error occurs if the key contains a value of the wrong type or contains a string that cannot be represented as integer. DECRBY operations are limited to 64 bit signed integers.