Unpivot

Converts columns back into rows.

Source data — Pattern 11: Interview SQL Patterns

All queries run against the shared employees table (see schema.sql). Topics 71 and 72 introduce an orders table to solve consecutive records and gaps-and-islands problems. Topics 73 and 74 introduce a monthly_sales table to demonstrate PIVOT and UNPIVOT operations.

Unpivot — source table 1

Unpivot — source table 2

Unpivot — source table 3

Unpivot — source table 4

What it does

Converts columns back into rows.

Problem

Convert monthly sales columns into rows.

SELECT *
FROM monthly_sales
UNPIVOT(amount FOR month IN (Jan,Feb,Mar));

Result

Unpivot — result 1