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 the ACID properties of a transaction?
ACID stands for Atomicity, Consistency, Isolation and Durability. A transaction either fully happens or not at all, leaves the data valid according to its rules, behaves as if it ran without interference from other transactions, and stays saved once committed, even if the server crashes.
BeginnerIn-depth3 min read - What do COMMIT, ROLLBACK and SAVEPOINT do?
COMMIT makes a transaction's changes permanent. ROLLBACK undoes everything since the transaction began. SAVEPOINT marks a point inside a transaction so you can roll back only part of it.
BeginnerQuick answer1 min read - What is autocommit and how does it affect transactions?
In autocommit mode every SQL statement is its own transaction and is committed as soon as it succeeds. To group statements into one atomic unit, start an explicit transaction with BEGIN or turn autocommit off.
BeginnerQuick answer1 min read