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30 September 2015
30 September 2015

Introduction to User-Defined Aggregate Functions

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OK, let’s speed past the easy bits, the parts we all already know: standard aggregate functions. Aggregate functions, unlike regular functions, take values from multiple rows as their input. The category includes those aggregate functions that are so ordinary they’re almost invisible – SUM, COUNT, MAX – and a couple that most of us never use – such as APPROX_COUNT_DISTINCT… Read more