Question
Which of the following integrity constraints ensures
that every non-null foreign key value must reference an existing primary key value in another table?Solution
Referential integrity enforces a relationship between two tables by ensuring that a foreign key in one table matches a valid primary key in another table. This constraint guarantees that the data is consistent and prevents "orphan" records. For example, in an "Orders" table with a foreign key referencing a "Customers" table, referential integrity ensures that every order must belong to an existing customer. If a foreign key value does not match any primary key value in the referenced table, the database system will reject the operation, ensuring data consistency. Why Other Options Are Incorrect:
- Option A: Entity integrity relates to primary keys, ensuring they are unique and not NULL. It does not address relationships between tables.
- Option C: Domain integrity enforces the validity of data types and permissible values for attributes, such as ensuring an "age" column only contains integers.
- Option D: Key integrity is not a formal term in relational database theory. It may be confused with primary or candidate key constraints but is not relevant here.
- Option E: Tuple integrity is not a standard concept in relational databases, making this option invalid.
Find which one of the given words cannot be made from the letters of the given word ‘ PERIPHERAL ’ .
...Find which one of the given words cannot be made from the letters of the given word.
‘ ENCOURAGEMENT ’
...Which among the following word cannot be formed using the letters of the given word only once?
ONDANSETRON
Select the word which cannot be formed using the letters of the given word using the letters only once.
REVERSIBLE
Select the option that is related to the third word in the same way as the second word is related to the first word.
Depression : Mood :: Insomnia : ?
- Which among the following words cannot be formed using the letters of the given word "PHOTOGRAPH" using each letter only once?
In the given words, if the 3rd and 6th (from the left end) letters are exchanged and same is done with 4th and 9t...
In the following question, select the word which cannot be formed using the letters of the given word.
IMPOSSIBLE
Statement: Â Â Â Â Â Â Â
Some Cream are Lotion. Â Â Â Â Â Â
No Lotion is Oil. Â Â Â Â Â Â Â
No Cream is Shampoo. Â Â Â Â Â
Statements: U > H < Y > S = B ≥ Z > F ≥ Q
Conclusion
I: Z < Y
II: B > Q
