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First and Last Touch SQL
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First and Last Touch SQL

MediumSQL · PostgreSQL

Problem

Write a SQL query using window functions to identify the first and last touchpoint of a user's conversion path.

Use the conversion_touchpoints table. Treat an earlier occurred_at as first, and use the lower touchpoint_id to break ties.

Output

  1. One row per user with user_id, first_touchpoint, and last_touchpoint.
  2. Include every user and order results by user_id ascending.

Schema

conversion_touchpoints
ColumnTypeDescription
touchpoint_idPKINTUnique identifier for the touchpoint event
user_idINTIdentifier of the user whose path contains the event
touchpointVARCHAR(100)Marketing or product touchpoint associated with the event
occurred_atTIMESTAMPTimestamp when the touchpoint occurred
Tablesconversion_touchpoints
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