[Solved] Given the table Employees with column Department containing values: 'Sales', NULL, 'HR', NULL, 'Sales', what will be the result of:SELECT Department, COUNT(*) FROM Employees GROUP BY Department;? | SQL

SQL - GROUP BY and HAVING

Given the table Employees with column Department containing values: 'Sales', NULL, 'HR', NULL, 'Sales', what will be the result of:
SELECT Department, COUNT(*) FROM Employees GROUP BY Department;?

A[{'Sales', 2}, {'HR', 1}, {NULL, 0}]

B[{'Sales', 2}, {'HR', 1}]

C[{'Sales', 2}, {'HR', 1}, {NULL, 1}, {NULL, 1}]

D[{'Sales', 2}, {'HR', 1}, {NULL, 2}]

Step-by-Step Solution

Solution:

Step 1: Identify groups formed by Department values
Departments are 'Sales', 'HR', and NULL. NULL values form one group.
Step 2: Count rows per group
'Sales' appears twice, 'HR' once, NULL twice.
Final Answer:
[{'Sales', 2}, {'HR', 1}, {NULL, 2}] -> Option D
Quick Check:
NULLs grouped together with count 2 [OK]

Quick Trick: NULLs count as one group with all NULL rows [OK]

Common Mistakes:

MISTAKES

Splitting NULLs into multiple groups
Ignoring NULL group in result
Counting NULL group as zero

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More SQL Quizzes

Given the table Employees with column Department containing values: 'Sales', NULL, 'HR', NULL, 'Sales', what will be the result of:

Step 1: Identify groups formed by Department values

Step 2: Count rows per group

Final Answer:

Quick Check:

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