How can you use PARTITION BY with ROW_NUMBER() to assign unique row numbers per department but restart numbering for each department, and also order employees by hire date ascending?

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PostgreSQL - Window Functions in PostgreSQL

How can you use PARTITION BY with ROW_NUMBER() to assign unique row numbers per department but restart numbering for each department, and also order employees by hire date ascending?

AROW_NUMBER() OVER (ORDER BY hire_date ASC PARTITION BY department)

BROW_NUMBER() PARTITION BY department ORDER BY hire_date ASC

CROW_NUMBER() OVER (PARTITION BY department ORDER BY hire_date ASC)

DROW_NUMBER() OVER (ORDER BY hire_date ASC)

Step-by-Step Solution

Solution:

Step 1: Recall correct syntax for ROW_NUMBER() with PARTITION BY
PARTITION BY and ORDER BY must be inside OVER() with PARTITION BY first.
Step 2: Identify correct option
ROW_NUMBER() OVER (PARTITION BY department ORDER BY hire_date ASC) correctly places PARTITION BY department then ORDER BY hire_date ASC inside OVER().
Final Answer:
ROW_NUMBER() OVER (PARTITION BY department ORDER BY hire_date ASC) -> Option C
Quick Check:
PARTITION BY before ORDER BY inside OVER() for ROW_NUMBER() [OK]

Quick Trick: Inside OVER(), PARTITION BY comes before ORDER BY [OK]

Common Mistakes:

Placing PARTITION BY outside OVER()
Swapping ORDER BY and PARTITION BY order
Omitting OVER() clause

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How can you use PARTITION BY with ROW_NUMBER() to assign unique row numbers per department but restart numbering for each department, and also order employees by hire date ascending?

Step 1: Recall correct syntax for ROW_NUMBER() with PARTITION BY

Step 2: Identify correct option

Final Answer:

Quick Check:

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