____specifies a search condition for a group or an aggregate.
Answer: B
Correct answer: HAVING Clause
HAVING applies its condition to groups after aggregation, which is why it can test an aggregate such as \( \text{SUM}(amount)>1000 \). WHERE is applied to individual rows before grouping and cannot see an aggregate at all.
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_____ command can be used to modify a column in a table
Answer: A
Correct answer: alter
ALTER TABLE changes the structure - adding, dropping or modifying a column. UPDATE changes the data inside existing columns, which is a different operation.
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Drop Table cannot be used to drop a table referenced by a ______ constraint.
Answer: C
Correct answer: Foreign Key
If another table's foreign key refers to this one, dropping it would leave those references pointing at nothing, so the DBMS refuses. The referencing constraint or table has to go first.
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The _______ is a set of programs to use and / or modify this data.
Answer: A
Correct answer: DBMS
The DBMS is the set of programs through which data is defined, stored, retrieved and modified. The database is the data; the DBMS is the software that manages it.
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The ______ indexes are forced to store only record IDs in the data structure and require at least one additional I/O Operation to retrieve the actual record.
Answer: C
Correct answer: Un-clustered
In a clustered index the rows are held in index order, so reaching the index entry reaches the row. An un-clustered index stores only a pointer or record id, so a second access is needed to fetch the row itself.
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The set of all values that can be taken by the attribute is called as _______ of the attribute.
Answer: D
Correct answer: Domain
The domain of an attribute is the set of values it may take - integers in a range, a list of permitted codes, dates. Cardinality is the number of tuples and degree the number of attributes.
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The full form of GUI is _________
Answer: C
Correct answer: Graphical User Interface
GUI stands for Graphical User Interface - an interface of windows, icons and pointers, as against a command line.
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The middleware databases in which the business rules act are applicable to _______ tier architectures
Answer: B
Correct answer: Three
A three-tier architecture separates presentation, application logic and data. The business rules live in the middle tier, which is what distinguishes it from two-tier, where the client holds them and talks to the database directly.
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The ______ key of a relation is the attribute (column) or collection of attributes, which uniquely identify a given tuple.
Answer: A
Correct answer: Primary
The primary key is the attribute or set of attributes chosen to identify each tuple uniquely. Candidate keys are all those that could serve; the one selected becomes the primary key and the rest are alternates.
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E-R Modeling is achieved by using ____ diagrams
Answer: D
Correct answer: E-R
Entity-relationship modelling is expressed in E-R diagrams: rectangles for entities, ovals for attributes, diamonds for relationships. DFDs model processes and Gantt charts schedules.
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