Entity integrity concerns the concept of uniqueness (also called no duplicate)
Uniqueness is enforced with:
Entity integrity is an integrity rule which states that every table must have a primary key and that the column or columns chosen to be the primary key should be unique and not null.
Asserting uniqueness of the entities within a data set implies that no:
exists more than once within the data set.
This attribute can be monitored two ways :
You can find duplicate records with the use of an Cryptography - Hash
The entity integrity is a data quality metrics.