Databases are essential for storing and managing data in many applications, from websites to banking systems. To ensure that these databases work correctly and reliably, they follow a set of principles known as ACID properties.
ACID Stands for Atomicity, Consistency, Isolation, Durability
<ol>
<li>Atomacity 
Atomacity ensures that every database transaction is treated as a single, indivisible unit. This means that a transaction either happens entirely or doesn’t happen at all. If any part of the transaction fails, the entire transaction is canceled, and the database remains unchanged.</li>
</ol>
Example:
Consider a banking transaction where $100 is transferred from Account A to Account B. This transaction involves two operations:
Debiting $100 from Account A.
Crediting $100 to Account B.
Atomicity ensures that either both operations are completed successfully, or neither operation is performed, preventing any partial updates to the database.
<ol start="2">
<li>Consistency 
Consistency ensures that a transaction can only bring the database from one valid state to another, following all the rules set for the data. This means the data must always be correct according to the database’s rules.</li>
</ol>
Example:
In a database of students and courses, a rule might state that a student cannot be enrolled in more than five courses at a time. If a transaction tries to enroll a student in a sixth course, consistency ensures that this transaction will not be allowed, keeping the data accurate and valid.
<ol start="3">
<li>Isolation 
Isolation means that transactions are performed independently, without interfering with each other. Even if multiple transactions are happening at the same time, they do not affect each other’s outcome.</li>
</ol>
Example:
Imagine two people are transferring money from and to the same bank account at the same time. Isolation ensures that each transaction is completed as if it were the only one happening, preventing errors and ensuring that both transactions are processed correctly.
<ol start="4">
<li>Durability 
Durability guarantees that once a transaction is completed and committed, it is permanently recorded in the database. Even if the system crashes right after the transaction, the changes made by the transaction will not be lost.</li>
</ol>
Example:
After successfully transferring $100 from account A to account B, the changes are saved to the database. If the system crashes immediately after, durability ensures that the $100 transfer is still recorded and not lost.

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Dev Squad

ACID properties (Atomicity, Consistency, Isolation, Durability) are principles used by databases to ensure correct and reliable transactions. Atomicity ensures transactions are all-or-nothing, Consistency ensures any transaction brings the database to a valid state, Isolation ensures transactions don't interfere with each other, and Durability ensures completed transactions are permanently recorded.

ACID Properties in Databases