What are transactions and how are they handled? Transactions allow multiple database operations to execute atomically — either all succeed or none do — ensuring data consistency. ● In MongoDB (using Mongoose): const session = await mongoose.startSession(); session.startTransaction(); try {

wait User.create([{ name: 'Bob' }], { session });

wait Order.create([{ userId: user._id }], { session });

wait session.commitTransaction();

} catch (error) {

wait session.abortTransaction();

} finally {

session.endSession();

}

• In Sequelize (MySQL/PostgreSQL):

const t = await sequelize.transaction();

try {

wait User.create({ name: 'Bob' }, { transaction: t });

wait Order.create({ userId: user.id }, { transaction: t });

wait t.commit();

} catch (error) {

wait t.rollback();

}

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