What will be the result if two transactions try to update the same record in the database simultaneously?

When two transactions attempt to update the same record in a database simultaneously, the outcome depends on the transaction isolation level and the locking mechanism in the DBMS.

Typically, the following occurs:

• The first transaction acquires a lock on the record and updates it.
• The second transaction waits for the lock to be released or encounters a lock error (deadlock).
• If the second transaction cannot acquire the lock, it may be rolled back or retried.

This prevents race conditions and ensures data integrity.

Example in Python using SQLite (which supports database-level locks):

import sqlite3

conn = sqlite3.connect('example.db')
cursor = conn.cursor()

try:
    cursor.execute('BEGIN TRANSACTION')
    cursor.execute('UPDATE users SET balance = balance + 100 WHERE id = 1')
    conn.commit()
except sqlite3.OperationalError:
    conn.rollback()

In real systems with more complex DBMSs (PostgreSQL, MySQL), behavior depends on transaction settings and isolation levels.