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Find the 2nd highest salary from the `employees` table.

Problem Statement

<p>Find the 2nd highest salary from the <code>employees</code> table.</p>

Examples

Input: employees table: +----+---------+--------+ | id | name | salary | +----+---------+--------+ | 1 | Alice | 5000 | | 2 | Bob | 6000 | | 3 | Charlie | 7000 | +----+---------+--------+

Output: +--------+ | salary | +--------+ | 6000 | +--------+

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

Complexity

Time Complexity: -

Space Complexity: -

Hints

šŸ’” Hint 1: Determine the sort order (ASC for ascending, DESC for descending) and whether only top records are required. šŸ’” Hint 2: Specify ORDER BY <column> [ASC|DESC] and append LIMIT <n> to cap the result set. šŸ’” Hint 3: Assemble: SELECT <cols> FROM <table> ORDER BY <col> [DESC] LIMIT <n>;

Editorial & Approach

Problem Overview & Intuition

To solve "Find Nth Highest Value", we query the relational database engine using declarative SQL. The goal is to find the 2nd highest 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

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

Optimal Implementation (SQL)

SELECT salary FROM employees ORDER BY salary DESC LIMIT 1 OFFSET 1;

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.

Find Nth Highest Value

Hard

Find the 2nd highest salary from the employees table.

Example Scenarios
1Example 1
Input:
employees table
idnamesalary
1Alice5000
2Bob6000
3Charlie7000
Output:
salary
6000
Explanation:

The query retrieves the requested records satisfying all problem requirements.

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