[Solved] You want to divide 7 employees into 3 salary groups using NTILE, but the salaries are:5000, 7000, 7000, 9000, 11000, 11000, 13000.Which NTILE(3) group assignment is correct when ordered by salary? | PostgreSQL

PostgreSQL - Window Functions in PostgreSQL

You want to divide 7 employees into 3 salary groups using NTILE, but the salaries are:
5000, 7000, 7000, 9000, 11000, 11000, 13000.
Which NTILE(3) group assignment is correct when ordered by salary?

A[{5000,1}, {7000,1}, {7000,1}, {9000,2}, {11000,2}, {11000,3}, {13000,3}]

B[{5000,1}, {7000,1}, {7000,2}, {9000,3}, {11000,3}, {11000,3}, {13000,3}]

C[{5000,1}, {7000,2}, {7000,2}, {9000,2}, {11000,3}, {11000,3}, {13000,3}]

D[{5000,1}, {7000,1}, {7000,2}, {9000,2}, {11000,3}, {11000,3}, {13000,3}]

Step-by-Step Solution

Solution:

Step 1: Calculate group sizes for 7 rows and 3 groups
7 rows divided into 3 groups: first group gets 3 rows, next two get 2 rows each.
Step 2: Assign groups by ordered salary
Order: 5000(1), 7000(1), 7000(2), 9000(3), 11000(3), 11000(3), 13000(3).
Final Answer:
[{5000,1}, {7000,1}, {7000,2}, {9000,3}, {11000,3}, {11000,3}, {13000,3}] -> Option B
Quick Check:
7 rows split into 3 groups: 3,2,2 [OK]

Quick Trick: Extra rows go to earlier groups; order matters [OK]

Common Mistakes:

Ignoring duplicate salaries affecting group boundaries
Assigning equal rows per group ignoring total rows
Misplacing group numbers for duplicates

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You want to divide 7 employees into 3 salary groups using NTILE, but the salaries are:

Step 1: Calculate group sizes for 7 rows and 3 groups

Step 2: Assign groups by ordered salary

Final Answer:

Quick Check:

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