Intergrity means something like 'be right' and consistent. The data in a database must be right and in good condition.
There are the domain integrity, the entity integrity, the referential integrity and the foreign key integrity constraints.
Domain intgrity means the definition of a valid set of values for an attribute. You define
- data type,
- lenght or size
- is null value allowed
- is the value unique or not
The entity integrity constraint states that primary keys can't be null. There must be a proper value in the primary key field.
The referential integrity constraint is specified between two tables and it is used to maintain the consistency among rows between the two tables.
An instructor Id. No. cannot be null, provided Instructor Id. No. being the primary key. - is valid
No two citizens have same Adhar-Id. - is valid
but, The budget of a company must be zero. --- is not a valid integrity constraint
so
option 3