GATE CS 2017 Set 1 — Question 23
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Databases → SQL → Aggregate Functions
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Question
Consider a database that has the relation schema EMP (EmpId, EmpName, and DeptName). An instance of the schema EMP and a SQL query on it are given below.
The output of executing the SQL query is _______.
| EmpId | EmpName | DeptName |
|---|---|---|
| 1 | XYA | AA |
| 2 | XYB | AA |
| 3 | XYC | AA |
| 4 | XYD | AA |
| 5 | XYE | AB |
| 6 | XYF | AB |
| 7 | XYG | AB |
| 8 | XYH | AC |
| 9 | XYI | AC |
| 10 | XYJ | AC |
| 11 | XYK | AD |
| 12 | XYL | AD |
| 13 | XYM | AE |
SELECT AVG(EC.Num)
FROM EC
WHERE (DeptName, Num) IN
(SELECT DeptName, COUNT(EmpId) AS
EC(DeptName, Num)
FROM EMP
GROUP BY DeptName)
Correct answer
2.6 to 2.6
Solution
The subquery calculates the count of employees for each department:
Average = .
- AA: 4 employees
- AB: 3 employees
- AC: 3 employees
- AD: 2 employees
- AE: 1 employee
Average = .
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