Pivot transformation of tables | Dataford Interview Questions

Given an input and output table, explain the steps required to convert the input table into the output table using a SQL pivot, then write the SQL query.

Asked in the R3 stage. Use the provided input table and produce the requested output shape.

Output

One row per service_line and account_name.
Columns: service_line, account_name, jan_volume, feb_volume, and mar_volume.
Sum duplicate records for the same service line, account, and period. Preserve missing monthly values as NULL.
Order by service_line, then account_name ascending.

Schema

input_volume

Column	Type	Description
input_idPK	INT	Unique input row identifier
service_line	VARCHAR(50)	Service line associated with the volume
account_name	VARCHAR(100)	Account associated with the volume
period	VARCHAR(10)	Reporting period
case_volume	INT	Number of cases recorded for the row

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Problem