1. What are Triggers? Explain and differentiate type of Triggers? 2. What are Views? Materialized View? 3. Explain Job role in the Current Company? 4. What is Index? Type of Indexes? Advantages and Drawbacks? 5. Difference in group by and having? 6. Write a query to get number of employee having same salary? 8. Mutating table error and Autonomous transaction? 9. Statement level and row level triggers?

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Overview of PL/SQL concepts including triggers, views, indexes, and more.

Triggers are database procedures that automatically execute in response to certain events on a table or view.
Types of triggers: BEFORE, AFTER, INSTEAD OF; e.g., BEFORE INSERT trigger to validate data before insertion.
Views are virtual tables based on the result of a query; Materialized Views store the result physically for faster access.
Indexes improve query performance by allowing faster data retrieval; types include B-tree, Bitmap, and Hash indexes.
GROUP BY aggregates data based on specified columns; HAVING filters groups based on a condition.
Query to find employees with the same salary: SELECT salary, COUNT(*) FROM employees GROUP BY salary HAVING COUNT(*) > 1;
Mutating table error occurs when a trigger tries to read or modify a table that is currently being modified; Autonomous transactions allow independent transaction management.
Statement-level triggers execute once per SQL statement; Row-level triggers execute for each row affected by the statement.

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