How Can I Use ROWNUM Effectively for Pagination in Oracle SQL Queries?

Mastering ROWNUM for Oracle SQL Pagination

This guide clarifies the effective use of ROWNUM for pagination in Oracle SQL queries. We'll address common pitfalls and demonstrate best practices.

*Why `SELECT FROM Person WHERE rownum > 100 AND rownum

ROWNUM assignment occurs after predicate filtering but before sorting or aggregation. Because ROWNUM is incremented sequentially after assignment, a condition like rownum > 1 will always return an empty set. The first row receives ROWNUM = 1, and the condition is never met.

The Limitations of SELECT ... FROM ... WHERE rownum BETWEEN lowerBound AND upperBound

Pre-12c Oracle versions don't support this direct BETWEEN approach for pagination. However, Oracle 12c and later versions offer superior OFFSET ... FETCH syntax (e.g., SELECT ... FROM ... OFFSET 4 ROWS FETCH NEXT 4 ROWS ONLY).

Suppressing the ROWNUM Column

To avoid displaying the ROWNUM column, explicitly list the desired columns in your SELECT statement instead of using SELECT *. For less frequent needs, the SQL*Plus NOPRINT command can temporarily hide unwanted columns.

Ensuring Accurate Pagination with ROWNUM

Correctly implemented, ROWNUM provides accurate pagination. The key is to first ORDER BY your data according to your desired sequence and then use ROWNUM to select a specific subset of rows. This sequential assignment characteristic of ROWNUM necessitates the ordering step.

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