How to use ROW_NUMBER() in MariaDB

Galaxy Glossary

How do I assign sequential row numbers in MariaDB?

ROW_NUMBER() assigns a unique sequential integer to each row within a query’s result set or a specified partition.

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Description

Example H2

Example H3

What does ROW_NUMBER() do in MariaDB?

ROW_NUMBER() returns an ascending integer starting at 1 for every row in the result set. When used with PARTITION BY, the count restarts for each partition.

What is the syntax for ROW_NUMBER()?

The window function’s general form is:

ROW_NUMBER() OVER ( [PARTITION BY expr_list] [ORDER BY sort_list] )

PARTITION BY groups rows before numbering, while ORDER BY defines numbering order.

How to generate simple row numbers?

SELECT ROW_NUMBER() OVER (ORDER BY id) AS rn, id, name, price FROM Products;

This query labels every product sequentially by primary key.

How to reset row numbers per customer?

SELECT customer_id, ROW_NUMBER() OVER (PARTITION BY customer_id ORDER BY order_date) AS order_seq, id AS order_id, order_date, total_amount FROM Orders;

Each customer’s orders start at 1, ordered by date.

How to identify the first product in each order?

SELECT oi.order_id, oi.product_id, oi.quantity, ROW_NUMBER() OVER (PARTITION BY oi.order_id ORDER BY oi.id) AS item_seq FROM OrderItems oi HAVING item_seq = 1;

The HAVING clause filters to the first row per order.

Best practices when using ROW_NUMBER()

Always add an ORDER BY inside OVER to guarantee deterministic numbering. Use indexed columns to keep the operation fast on large datasets.

What common mistakes should I avoid?

Omitting ORDER BY yields an indeterminate sequence. Forgetting PARTITION BY when needed causes numbering to continue across groups.

Why How to use ROW_NUMBER() in MariaDB is important

How to use ROW_NUMBER() in MariaDB Example Usage


-- Top 3 most expensive products per order
WITH ranked_items AS (
  SELECT 
      order_id,
      product_id,
      price * quantity AS item_total,
      ROW_NUMBER() OVER (PARTITION BY order_id ORDER BY price * quantity DESC) AS price_rank
  FROM OrderItems oi
  JOIN Products p ON p.id = oi.product_id
)
SELECT order_id, product_id, item_total
FROM ranked_items
WHERE price_rank <= 3;

How to use ROW_NUMBER() in MariaDB Syntax


ROW_NUMBER() OVER (
    [PARTITION BY partition_expression [, ...]]
    [ORDER BY sort_expression [ASC|DESC] [, ...]]
)

-- Example in an ecommerce context
SELECT 
    ROW_NUMBER() OVER (PARTITION BY customer_id ORDER BY order_date DESC) AS order_rank,
    id AS order_id,
    customer_id,
    order_date,
    total_amount
FROM Orders;

Common Mistakes

Mistake: Omitting ORDER BY inside OVER. Why it’s wrong: Without order, MariaDB may number rows in any sequence, leading to unpredictable results. Fix: Always specify ORDER BY with a deterministic column.
Mistake: Forgetting PARTITION BY when grouping is required. Why it’s wrong: Numbers continue across the whole set, breaking per-group logic. Fix: Add PARTITION BY to restart numbering for each logical group.