How to Select the nth Row from a SQL Table Across Different Database Systems?

Cross-Database Strategies for Selecting the nth Row in SQL

This article examines techniques for retrieving the nth row from a SQL table, offering solutions compatible with various database systems.

General Approaches

The SQL standard lacks a direct command for this task. However, several common methods exist:

• Window Functions: Employ window functions like ROW_NUMBER() to assign a unique rank to each row. Subsequently, filter the result set to retrieve the row with the desired rank.
• LIMIT and OFFSET: Databases such as PostgreSQL and MySQL offer LIMIT and OFFSET clauses. OFFSET skips a specified number of rows, while LIMIT restricts the output to a certain number of rows.

Database-Specific Implementations

SQL Server:

<code class="language-sql">WITH RankedRows AS (
  SELECT ROW_NUMBER() OVER (ORDER BY OrderID) AS RowNum, OrderID, OrderDate
  FROM Orders
)
SELECT *
FROM RankedRows
WHERE RowNum = 1000000;</code>

MySQL / PostgreSQL:

<code class="language-sql">SELECT *
FROM your_table
LIMIT 1 OFFSET (n - 1);</code>

Oracle / DB2 / SQL Server (Alternative):

<code class="language-sql">SELECT * FROM (
  SELECT
    ROW_NUMBER() OVER (ORDER BY key ASC) AS rn,
    columns
  FROM tablename
) AS ranked_rows
WHERE rn = n;</code>

PostgreSQL 8.4 / SQLite 3.25.0 :

<code class="language-sql">SELECT *
FROM your_table
OFFSET (n - 1) ROWS
FETCH FIRST 1 ROW ONLY;</code>

This provides a comprehensive overview of how to efficiently select the nth row across multiple database systems. Remember to replace placeholders like your_table, key, columns, and n with your actual table and column names, and the desired row number.

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