1. | The SQL database language includes statements for: |
a. | Database definition. |
b. | Database manipulation. |
c. | Database control. |
d. | All of the above. |
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Answer: (d).All of the above.
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2. | A command to remove a relation from an SQL database |
a. | Delete table table name |
b. | Drop table table name |
c. | Erase table table name |
d. | Alter table table name |
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Answer: (b).Drop table table name
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3. | Which SQL Query is use to remove a table and all its data from the database? |
a. | Create Table |
b. | Alter Table |
c. | Drop Table |
d. | None of these |
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Answer: (c).Drop Table
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4. | A type of query that is placed within a WHERE or HAVING clause of another query is called |
a. | Super query |
b. | Sub query |
c. | Master query |
d. | Multi-query |
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Answer: (b).Sub query
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5. | Aggregate functions are functions that take a ___________ as input and return a single value. |
a. | Collection of values |
b. | Single value |
c. | Aggregate value |
d. | Both a & b |
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Answer: (a).Collection of values
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6. | Select __________ from instructor where dept name= ’Comp. Sci.’; Which of the following should be used to find the mean of the salary ? |
a. | Mean(salary) |
b. | Avg(salary) |
c. | Sum(salary) |
d. | Count(salary) |
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Answer: (b).Avg(salary)
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7. | All aggregate functions except _____ ignore null values in their input collection. |
a. | Count(attribute) |
b. | Count(*) |
c. | Avg |
d. | Sum |
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Answer: (b).Count(*)
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8. | A Boolean data type that can take values true, false, and________ . |
a. | 1 |
b. | 0 |
c. | Null |
d. | Unknown |
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Answer: (d).Unknown
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9. | Select count (____ ID) from teaches where semester = ’Spring’ and year = 2010; If we do want to eliminate duplicates, we use the keyword ______in the aggregate expression. |
a. | Distinct |
b. | Count |
c. | Avg |
d. | Primary key |
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Answer: (a).Distinct
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10. | The ____ connective tests for set membership, where the set is a collection of values produced by a select clause. The ____ connective tests for the absence of set membership. |
a. | Or, in |
b. | Not in, in |
c. | In, not in |
d. | In, or |
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Answer: (c).In, not in
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