डाटाबेस र DBMS – Database & DBMS MCQ
डाटाबेस र DBMS – कम्प्युटर र IT
Database & DBMS · Computer & IT (Technical) · ५६३ प्रश्न
५६३ प्रश्न उपलब्ध। मोड छान्नुहोस्:
डाटाबेस र DBMS: प्रश्न र उत्तर
सही लागेको विकल्पमा थिच्नुहोस्। सही भए हरियो, गलत भए रातो देखिन्छ; ३ सेकेन्डपछि सही उत्तर र व्याख्या देखिन्छ।
सही: ० / ०
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Relation R(A, B, C) has functional dependencies AB → C and C → B. Its candidate keys are AB and AC. The highest normal form of R is:
सही उत्तर: क) 3NF
All attributes are prime, so R is in 3NF; but in C → B the determinant C is not a super key, so R is not in BCNF.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Relation R(A, B, C, D, E) has functional dependencies AB → C, C → D and D → E, and AB is its only candidate key. The highest normal form R satisfies is:
सही उत्तर: घ) 2NF
No non-key attribute depends on part of AB, so R is in 2NF; but C → D and D → E are transitive dependencies, so R is not in 3NF.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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The Armstrong axiom which states that if X → Y then XZ → YZ is the rule of:
सही उत्तर: ग) Augmentation
Augmentation allows the same attributes to be added to both sides of a functional dependency.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A functional dependency X → Y is called trivial when:
सही उत्तर: ख) Y is a subset of X
For example AB → A is trivial because it always holds; such dependencies give no information about the data.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Unwanted problems such as being unable to add data without other data, or losing information when a row is deleted, in a poorly designed table are called:
सही उत्तर: क) Anomalies (insertion, deletion and update)
Insertion, deletion and update anomalies arise from redundancy and are removed by normalization.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A named, precompiled set of SQL statements stored in the database that applications call explicitly, possibly with parameters, is a:
सही उत्तर: घ) Stored procedure
Stored procedures run on the database server when called (e.g., CALL or EXEC), reducing network traffic and reusing logic.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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A set of SQL statements stored in the database and executed automatically when an INSERT, UPDATE or DELETE occurs on a table is a:
सही उत्तर: ग) Trigger
Triggers fire automatically on specified events and are used for auditing, enforcing rules or maintaining derived data.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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With ON DELETE SET NULL on a foreign key, deleting a parent row:
सही उत्तर: ख) Sets the foreign key in the matching child rows to NULL
SET NULL keeps the child rows but breaks their link to the deleted parent; CASCADE would delete them instead.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which SQL constraint supplies a value automatically when an INSERT does not specify a value for that column?
सही उत्तर: क) DEFAULT
For example, status VARCHAR(10) DEFAULT 'Active' stores 'Active' when no status is given.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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Which SQL constraint ensures all values in a column are different but, unlike PRIMARY KEY, normally permits NULL values?
सही उत्तर: घ) UNIQUE
UNIQUE forbids duplicate non-NULL values; a table can have several UNIQUE constraints but only one primary key.
💬 टिप्पणी / गल्ती रिपोर्ट (०)
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