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N036-E1 Tier 3 · Intermediate · easy ecommerce · Brightlane

Return the result of concatenating `'ORDER-'` and `'1042'` with the `||` operator

Part of String Concatenation and Formatting in SQL

The problem

Brightlane's reporting system builds order reference strings by combining a prefix and an order identifier.

Write a query to return the result of concatenating 'ORDER-' and '1042' with the || operator.

Output:

  • A single row with one column, order_ref, containing the concatenated string.
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
  'ORDER-' || '1042' AS order_ref

The shape

'ORDER-' || '1042' joins the two string literals end-to-end and returns the single concatenated value 'ORDER-1042'. That is the order reference the reporting system needs.

Clause by clause

  • SELECT 'ORDER-' || '1042' AS order_ref evaluates the concatenation once and labels the resulting column order_ref. The || operator takes the two adjacent string literals and returns a single string with the right operand pasted onto the end of the left. There is no FROM because both values come straight from the prompt as literals; nothing is being read from a table.

Why this and not CONCAT('ORDER-', '1042')

Both expressions return the same string on this input. || reads as a binary operator between two values, which matches the shape of the operation: two strings, one join. CONCAT is variadic and takes a function-call form, which carries more visual weight than the work being done. Either is correct on a clean two-operand join with no NULLs in play. The choice between them becomes load-bearing only when a NULL might appear, which is the next problem.

You practiced || — the strict two-operand concatenation operator; both sides must be present to produce a result.

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