Question: For each of the SQL aggregate functions sum count min and

For each of the SQL aggregate functions sum, count, min and max, show how to compute the aggregate value on a multiset S1 ∪ S2, given the aggregate values on multisets S1 and S2.
Based on the above, give expressions to compute aggregate values with grouping on a subset S of the attributes of a relation r (A, B, C, D, E), given aggregate values for grouping on attributes T ⊇ S, for the following aggregate functions:
a. sum, count, min and max
b. avg
c. standard deviation

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  • CreatedJanuary 29, 2011
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