Difference between Delete vs Truncate DELETE is used to remove rows from a table based on specified conditions. TRUNCATE removes all rows in a table without any conditions. It cannot be used to selectively delete specific rows.

Difference between Where vs Having Context: WHERE is used to filter rows based on individual records before any grouping or aggregation. HAVING is used to filter the results of a query based on aggregated values after grouping.

Index is a data structure (like dictionary) that improves the speed of data retrieval operations on a database table at the cost of additional writes and storage space. Indexing involves creating an organized structure that allows the database management system (DBMS) to locate and access rows more efficiently based on the values in one or more columns.