42. | A primary key is which of the following? |
Discuss |
Answer: (b).An attribute that uniquely identifies each row
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43. | A foreign key is which of the following? |
Discuss |
Answer: (c).An attribute that serves as the primary key of another relation
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45. | A relation has which of the following properties? |
Discuss |
Answer: (c).Each relation has a unique name.
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46. | The entity integrity rule states that: |
Discuss |
Answer: (a).no primary key attribute may be null.
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47. | When mapping a multivalued attribute into a relation which of the following is true? |
Discuss |
Answer: (b).Two relations are created.
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48. | When mapping a regular entity into a relation which of the following is true? |
Discuss |
Answer: (a).One relation is created.
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49. | When mapping a binary many-to-many relationship into a relation which of the following is true? |
Discuss |
Answer: (c).Three relations are created.
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50. | When mapping a many-to-many unary relationship into a relation which of the following is true? |
Discuss |
Answer: (b).Two relations are created.
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