Calculate the median salary from the `employees` table.

Problem Statement

<p>Calculate the median salary from the <code>employees</code> table.</p>

Examples

Input: employees table: +----+--------+ | id | salary | +----+--------+ | 1 | 50000 | | 2 | 60000 | | 3 | 70000 | | 4 | 80000 | | 5 | 90000 | +----+--------+

Output: +---------------+ | median_salary | +---------------+ | 70000 | +---------------+

Explanation: The query retrieves the requested records satisfying all problem requirements.

Complexity

Time Complexity: -

Space Complexity: -

Hints

💡 Hint 1: Identify the filtering conditions needed to isolate the target rows from the table. 💡 Hint 2: Use appropriate operators: = for exact matches, LIKE for wildcard patterns, IN for sets, or BETWEEN for numeric/date ranges. 💡 Hint 3: Combine filters with AND/OR if multiple conditions exist: SELECT <cols> FROM <table> WHERE <condition>;

Editorial & Approach

Problem Overview & Intuition

To solve "Median Calculation", we query the relational database engine using declarative SQL. The goal is to calculate the median salary from the `employees` table. By formulating an optimal execution plan with appropriate projection and filtering, the database engine executes the query with minimal overhead.

Step-by-Step Approach

Analyze Schema: Identify the target tables, necessary foreign keys, and expected output columns.
Construct Filtering & Logic: Apply row projections to isolate the requested data.
Format & Order: Sort the resulting records according to specified order criteria.

Optimal Implementation (SQL)

SELECT PERCENTILE_CONT(0.5) WITHIN GROUP (ORDER BY salary) AS median_salary FROM employees;

Complexity Analysis

Time Complexity O(N log N) for sorting or partitioning rows.

Space Complexity O(N) for intermediate group hash tables or window buffers.

Key Considerations & Edge Cases

Empty Tables: The query executes safely returning zero rows without syntax error.
NULL Values: Columns containing NULL values are properly handled by standard ANSI SQL semantics.
Case Sensitivity: String comparisons and keywords adhere to PostgreSQL/standard SQL rules.

Median Calculation

Hard

Calculate the median salary from the employees table.

Example Scenarios

1Example 1

Input:

employees table

id	salary
1	50000
2	60000
3	70000
4	80000
5	90000

Output:

median_salary
70000

Explanation:

The query retrieves the requested records satisfying all problem requirements.

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