In MySQL, ANY_VALUE() is an aggregate function that allows us to include nonaggregated columns in the SELECT list when using the GROUP BY clause.
The ANY_VALUE() function is commonly used to resolve issues that arise when a query includes columns that are not part of the GROUP BY clause or aggregate functions. It can be useful in scenarios where we want to include descriptive columns in a grouped result set without affecting the grouping behaviour.
If you’re getting an error that reads “LIMIT is only supported in combination with either BYSCORE or BYLEX” it’s probably because you’re trying to use the LIMIT clause without using the BYSCORE or BYLEX arguments.
This can happen when using the VRANGE command without either of the BYSCORE or BYLEX arguments.
To fix this issue, use either the BYSCORE or BYLEX argument when using the command. This obviously means that we need to adjust our query so that it’s querying by score or lexicographically.
When we create a sequence in PostgreSQL, we have the option of making it a non-repeating sequence or repeating sequence.
By “repeating” sequence, I mean that, once it reaches its maximum value (or minimum if it’s a descending sequence), it starts all over again, re-using numbers previously generated.
Continue readingMySQL provides us with a handy WITH ROLLUP modifier that allows us to get totals and subtotals when using the GROUP BY clause.
Below is an example of how the MySQL WITH ROLLUP modifier works.
If you’re getting error msg 6358 which reads something like 300 is not a valid style number when converting to XML, it’s probably because you’re trying to convert a value to XML, but the style that you’re specifying isn’t supported for conversions to that data type.
It’s not that the conversion can’t happen, it’s just that it can’t happen using the style that you’re specifying.
Continue readingMySQL provides us with a bunch of functions and operators that allow us to search JSON documents for various things, such as specific values, paths, keys, etc.
Here are seven functions and three operators that search JSON documents in MySQL.
Continue readingIn MySQL, the VAR_SAMP() function returns the sample variance of an expression. The denominator is the number of rows minus one.
If there are no matching rows, or if the expression is NULL, VAR_SAMP() returns NULL.
VAR_SAMP() is an aggregate function, and so it can be used with the GROUP BY clause.
The VAR_SAMP() function can also be used as a window function.
In MySQL, the VARIANCE() function returns the population standard variance of an expression.
If there are no matching rows, or if the expression is NULL, the function returns NULL.
The VARIANCE() function is a synonym for the standard SQL VAR_POP() function. In other words, they both do the same thing, but VARIANCE() is not standard SQL. Therefore, if you need to use standard SQL, use VAR_POP() instead.
If you get an error that reads “WRONGTYPE Operation against a key holding the wrong kind of value” when using the ZCOUNT command in Redis, it’s probably because you’re passing a key with the wrong data type.
To fix this issue, be sure that the key you pass to the ZCOUNT command holds a sorted set.
In MySQL, the VAR_POP() function returns the population standard variance of an expression.
If there are no matching rows, or if the expression is NULL, VAR_POP() it returns NULL.
VAR_POP() is an aggregate function, and so it can be used with the GROUP BY clause.
The VAR_POP() function is standard SQL. There’s also a VARIANCE() function that does the same thing, but is not standard SQL.