[Q.26] Which type of SQL join returns all rows from the left table and matched rows from the right table?
LEFT JOIN returns all left table records regardless of match in right table.
[Q.27] A table is in Boyce-Codd Normal Form (BCNF) if for every functional dependency X -> Y:
BCNF strictly requires left hand side X of every non-trivial FD to be a super key.
[Q.28] Which clause in SQL is used to filter records AFTER an aggregate function (such as GROUP BY) is applied?
HAVING filters grouped/aggregated rows; WHERE filters individual rows before grouping.
[Q.29] In an ER diagram, an attribute composed of multiple sub-attributes (e.g. Name split into First_Name, Last_Name) is called a:
Composite attributes can be divided into smaller sub-parts.
[Q.30] Which storage class in SQL is designed to store large unstructured binary data like images or audio files?
BLOB (Binary Large Object) holds unstructured binary media.