Author: Ian

Fix “LIMIT is only supported in combination with either BYSCORE or BYLEX” in Redis

Posted on by Ian

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.

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Fix Error 6358 “…is not a valid style number when converting to XML” in SQL Server

Posted on by Ian

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.

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Understanding the VAR_SAMP() Function in MySQL

Posted on by Ian

In 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.

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How VARIANCE() Works in MySQL

Posted on by Ian

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.

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Understanding the VAR_POP() Function in MySQL

Posted on by Ian

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.

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Understanding the STDDEV_SAMP() Function in MySQL

Posted on by Ian

In MySQL, the STDDEV_SAMP() function returns the sample standard deviation of a given expression. This is the square root of VAR_SAMP().

STDDEV_SAMP() is an aggregate function, and so it can be used with the GROUP BY clause.

If there are no matching rows, or if the expression is NULL, STDDEV_SAMP() returns NULL.

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