Interview Q&A / SQL & DBMS
SQL & DBMS interview questions
Joins, keys, normalisation, indexes and transactions for placement and backend interviews.
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- What are insertion, update and deletion anomalies?
They are problems in a badly designed table where redundant data forces you to add dummy values, edit many rows for one change, or lose unrelated facts when deleting a row. Normalization removes them.
BeginnerQuick answer1 min read - What does a table need to be in First Normal Form, and what breaks it?
A table is in 1NF when every column holds a single atomic value, there are no repeating groups, and each row is unique. Storing a comma-separated list of values in one cell breaks 1NF.
BeginnerQuick answer1 min read - What is a functional dependency in DBMS?
A functional dependency X -> Y means that if two rows have the same X value they must have the same Y value, so X determines Y. Normalization is built on finding and organizing these dependencies.
BeginnerQuick answer1 min read