Let's dive into two essential tools: Cursors and Triggers.
These aren't just academic concepts; they're the keys to building robust, self-managing data layers.
- Cursors: Mastering Row-by-Row Logic A Cursor allows you to iterate through the result set of a query, one row at a time. This is crucial when you need to apply complex logic (like calculations or conditional updates) to individual records that a single UPDATE statement can't handle.
💡 Use Case: Finding High-Salary Employees
We want to process the names of all employees earning over $50,000 from the Employee table.
We'll use the clean, modern Cursor FOR Loop (PL/SQL syntax) that handles the OPEN, FETCH, and CLOSE operations automatically.
- Triggers: The Silent Data Guardians A Trigger is a piece of procedural code that executes automatically in response to a specific event (INSERT, UPDATE, or DELETE) on a table. It's the perfect tool for ensuring data integrity and auditing without relying on application code.
💡 Use Case: Auto-Logging Student Registrations
Whenever a new student is added to the Students table, we want to log the event in a Student_Audit table.
This AFTER INSERT trigger fires after the new student is created and logs the new row's ID into the audit table.
Conclusion
Cursors give you iteration control for complex logic, and Triggers give you automatic auditing and integrity for events. Use them wisely—while powerful, excessive or poorly designed cursors can hurt performance.
Thank you @santhoshnc sir for guiding me
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