Compute Z Score

MediumSQL · PostgreSQL

Problem

Calculate Z score on a table with some sales data

Asked in the technical interview stage. SQL on a sales table. Write a query that calculates the z score for each sale using the non-null sales amounts.

Output

One row per sale with a non-null amount
Columns: sale_id, sale_amount, and z_score
Round z_score to four decimal places and order by sale_id ascending

Schema

sales

Column	Type	Description
sale_idPK	INT	Unique identifier for the sale
sale_amount	NUMERIC(10,2)	Sales amount used in the calculation

Tablessales

CodePostgreSQL

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