Fix “WRONGTYPE Operation against a key holding the wrong kind of value” when using ZUNION or ZUNIONSTORE in Redis

If you get an error that reads “WRONGTYPE Operation against a key holding the wrong kind of value” when using the ZUNION or ZUNIONSTORE commands in Redis, it’s because you’re passing a key with the wrong data type.

To fix this issue, make sure the keys you pass to these commands contain either sets or sorted sets. Although these commands are for sorted sets, they also work with non-sorted sets.

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Redis ZREVRANGE Replacement

Starting with Redis 6.2.0, the ZRANGE command added the REV, BYSCORE, BYLEX and LIMIT options. The addition of the first three means that the ZRANGE command can now do what the ZREVRANGE, ZRANGEBYSCORE, ZREVRANGEBYSCORE, ZRANGEBYLEX and ZREVRANGEBYLEX commands can do.

As a result, those commands are now deprecated (as of Redis 6.2.0).

Therefore, we should no longer use the ZREVRANGE command when we need to return a sorted set in descending order. Instead, we should use the ZRANGE command with the REV argument.

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Get All Parameters from a SQL Server Database (T-SQL)

In SQL Server we can query the sys.parameters system catalog view to return all parameters that belong to user-defined objects.

For system objects, we can query the sys.system_parameters view. We can alternatively query the sys.all_parameters system catalog view to return all parameters that belong to either user-defined or system objects.

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Redis ZRANGEBYSCORE Replacement

Starting with Redis 6.2.0, the ZRANGE command added the REV, BYSCORE, BYLEX and LIMIT options. The addition of the first three options means that the ZRANGE command can now do what the ZREVRANGE, ZRANGEBYSCORE, ZREVRANGEBYSCORE, ZRANGEBYLEX and ZREVRANGEBYLEX commands can do.

As a result, those commands are now deprecated (as of Redis 6.2.0).

Therefore, we should no longer use the ZRANGEBYSCORE command when we need to return a sorted set by score. Instead, we should use the ZRANGE command with the BYSCORE argument.

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Fix ERROR 1050 (42S01) “Table … already exists” in MySQL

If you’re getting an error that reads something like “ERROR 1050 (42S01): Table ‘customers’ already exists” when trying to create a table in MySQL, it’s probably because there’s already a table in the database with the same name.

To fix this issue, either change the name of the table you’re trying to create, or check the existing table to see if it’s the one you actually need.

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