Which of the following are relational integrity constraints?
Which of the following are relational integrity constraints?
The correct option is B All of the above
Relational integrity constraints are:-
1) Null value:-
The entity
integrity constraint states that primary keys can't be null. There must be a proper value in the primary key field. This
is because the primary key value
is used to identify individual rows in a table. Null value is different from zero value or space.
2) Primary key:- Primary key is a special relational
database table column (or combination of columns) designated to uniquely
identify all table records. Primary
key's main features are: It must contain a unique value for each row of
data.
3) Referential integrity:-
Referential integrity (RI) is a
relational database concept, which states that table relationships must always
be consistent. In other words, any foreign key field must agree with the
primary key that is referenced by the foreign key.
Relational integrity constraints are:-
1) Null value:-
The entity integrity constraint states that primary keys can't be null. There must be a proper value in the primary key field. This is because the primary key value is used to identify individual rows in a table. Null value is different from zero value or space.
2) Primary key:- Primary key is a special relational database table column (or combination of columns) designated to uniquely identify all table records. Primary key's main features are: It must contain a unique value for each row of data.
3) Referential integrity:-
Referential integrity (RI) is a relational database concept, which states that table relationships must always be consistent. In other words, any foreign key field must agree with the primary key that is referenced by the foreign key.
