A Comparison of 6 SQL Rank Functions

SQL rank functions can be handy things to have when analysing data. Most major RDBMSs implement a similar bunch of ranking functions, usually with the same names. These rank functions allow us to assign rankings to rows based on specific criteria.

In this article, we’ll look at six commonly used SQL ranking functions, and observe how they differ. We’ll throw them all together into a single query and see their results side by side.

The rank functions in question are: ROW_NUMBER(), RANK(), DENSE_RANK(), NTILE(), PERCENT_RANK(), and CUME_DIST().

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Understanding the Difference Between SCALE(), MIN_SCALE() and TRIM_SCALE() in PostgreSQL

Anyone who looks at PostgreSQL’s list of mathematical functions will notice that there are some functions that have “scale” in their name. In particular, scale(), min_scale(), and trim_scale().

While these functions all have a similar name, they each have a different purpose. That said, they’re all related to the scale of the given number. The scale is the number of digits to the right of the decimal point in a number. For example, the number 1.95 has a scale of 2, and 1.958 has a scale of 3.

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A Quick Look at the FACTORIAL() Function in PostgreSQL

In PostgreSQL, factorial() is a mathematical function that returns the factorial of a given integer. We pass the integer (it accepts bigint), and it returns the factorial as a numeric value.

In mathematics, the factorial is the product of all positive integers less than or equal to a given positive integer. It’s denoted by that integer and an exclamation point.

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