हम सभी लोग जानते हैं कि इस टाइम पर ऑनलाइन परीक्षा बहुत कठिन परीक्षाओं में से एक है, इसलिए हम आप लोगो के लिये DBMS की बेहतर क्विज लेकर आये है , जो कि बहुत महत्वपूर्ण है। यदि आप उस समय अधिक स्कोर प्राप्त करना चाहते हैं तो आपको D.B.M.S. क्विज का डेली प्रयास करना होता है |
|| चलिये अब हम चलते है अपनी क्विज पर ||
आओ स्टार्ट करें क्वेश्चनों की कहानी |
जो आप को बनायेगी सबसे अलग | |
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1. Consider attributes ID, CITY and NAME. Which one of this can be considered as a super key?
Explain:- Here the id is the only attribute which can be taken as a key. Other attributes are not uniquely identified.
2. The subset of a super key is a candidate key under what condition?
Explain:- The subset of a set cannot be the same set. Candidate key is a set from a super key which cannot be the whole of the super set..
3. A _____ is a property of the entire relation, rather than of the individual tuples in which each tuple is unique.
Explain:- Key is the constraint which specifies uniqueness.
4. Which one of the following attribute can be taken as a primary key?
Explain:- The attributes name, street and department can repeat for some tuples. But the id attribute has to be unique. So it forms a primary key.
5. Which one of the following cannot be taken as a primary key?
Explain:- Street is the only attribute which can occur more than once.
6. Which one of the following is a set of one or more attributes taken collectively to uniquely identify a record?
Explain:- Super key is the superset of all the keys in a relation.
7. An attribute in a relation is a foreign key if the _______ key from one relation is used as an attribute in that relation.
Explain:- The primary key has to be referred in the other relation to form a foreign key in that relation.
8. The relation with the attribute which is the primary key is referenced in another relation. The relation which has the attribute as a primary key is called ______________
Explain:- None
9. The ______ is the one in which the primary key of one relation is used as a normal attribute in another relation.
Explain:- None
Explain:- A relation, say r1, may include among its attributes the primary key of another relation, say r2. This attribute is called a foreign key from r1, referencing r2. The relation r1 is also called the referencing relation of the foreign key dependency, and r2 is called the referenced relation of the foreign key.