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.
In Redis, the COPY command copies the value from one key to another.
This command was introduced in Redis 6.2.0.
In 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.
In Redis, the DECR command decrements the value of a specified key by one.
If the key doesn’t exist, DECR creates the key with a value of 0 and then decrements it by one.
An error occurs if the key contains a value of the wrong type or contains a string that cannot be represented as integer.
In Redis, the INCRBYFLOAT command increments a floating point number by the specified amount. More specifically, it increments the string representing a floating point number stored at the specified key.
If the key doesn’t exist, INCRBYFLOAT creates the key with a value of 0 and then increments it by the specified amount.
An error occurs if the key contains a value of the wrong type, or if the current key content or the specified increment are not parsable as a double precision floating point number.
When we have a table with a generated column, here are two methods we can use to return its definition.