Maximum two queries and statistical queries in an SQL data table

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The answer is:

Select * from hard

Where je in (select Top 2 je from hard B where a. Qu = B. Qu order by je) 

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Two methods of statistical query:

(1 ),Query the student numbers and affiliated organizations of more than 5 Elective Courses

The answer is:

Select Sn, SD from S

Where s # In (select s # from SC group by S # Having count (distinct C #)> 5)

(2 ),

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The answer is incorrect. Correct the following:

Select distinct .*

From DBO. hc a left join DBO. HC B

On a. Caller number = B. Caller Number

Where a. ID <> B. ID and (datediff (second, A. Call start time, B. Call End Time)> 10)

And
Datediff (second, B. Call end time, A. Call Start Time)> 10)

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