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LAG analytic
Learn LAG analytic in Oracle SQL through the exact construct, a dedicated example, a boundary case, and a mastery check.
LAG analytic is an atomic Oracle SQL lesson inside Hierarchical & Analytic SQL. The example uses the specific syntax, command, API, instruction, or language rule named by this lesson.
Study the construct itself, then change one relevant input and predict the result before running it. That keeps this lesson focused on LAG analytic rather than on generic Oracle SQL syntax.
Topic-specific example
SELECT day,total,LAG(total) OVER(ORDER BY day) prev FROM sales;
Test LAG analytic with an empty result, NULL/missing value, duplicate key, or concurrent operation where relevant; database behavior should be verified at the boundary shown by this example.