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N002-E2 Tier 1 · Foundations · easy ecommerce · Brightlane

Return the name and email of every customer

Part of FROM and Table References in SQL

The problem

Brightlane's CRM team is migrating to a new email platform and needs a full contact export to seed the new system.

Write a query to return the name and email of every customer.

Assumptions:

  • The customers table contains every customer Brightlane has on file.
  • Each customer has a name and an email recorded.

Output:

  • One row per customer, with columns name and email.
Schema · ecommerce 5 tables
categories
id integer
name text
parent_id? integer
products
id integer
name text
category_id integer
price numeric
stock_qty integer
attributes? jsonb
order_items
id integer
order_id integer
product_id integer
quantity integer
unit_price numeric
customers
id integer
name text
email text
city? text
country text
created_at timestamptz
is_active boolean
orders
id integer
customer_id integer
ordered_at timestamptz
status text
total_amount numeric
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Solution query
SELECT
  name,
  email
FROM
  customers

The shape

FROM customers is the row source, and naming name and email in the SELECT list trims every row down to the two fields the email platform needs to seed a contact.

Clause by clause

  • SELECT name, email keeps only the two columns the migration cares about. The customers table likely holds plenty of other fields — created-at timestamps, addresses, whatever else Brightlane records — and none of them need to go to the new platform. Naming the two relevant columns is how the query filters horizontally: the rows stay, the irrelevant columns drop.
  • FROM customers reads every customer row Brightlane has on file. With no WHERE clause, the full population comes through — active customers, inactive ones, recent signups, everyone. That's the right shape for a contact export seeding a new system from scratch.

Why this and not SELECT *

SELECT * feels like "give me everything," but the new email platform doesn't need everything. It needs names and emails. Naming the two columns the consumer needs keeps the export tight and the contract explicit: this query produces a two-column file, today and next quarter, regardless of what columns get added to customers later.

You practiced selecting only the columns you need from a table rather than returning every column. Picking columns explicitly is what keeps query results focused and stable as the underlying schema changes.

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