Replace all occurrences of "HR" with "Human Resources" in the `department` column.
Problem Statement
Examples
Input: employees table: +----+---------+------------+ | id | name | department | +----+---------+------------+ | 1 | Alice | HR | | 2 | Bob | IT | | 3 | Charlie | HR | +----+---------+------------+
Output: +---------+-----------------+ | name | department | +---------+-----------------+ | Alice | Human Resources | | Bob | IT | | Charlie | Human Resources | +---------+-----------------+
Explanation: The query retrieves the requested records satisfying all problem requirements.
Complexity
Time Complexity: -
Space Complexity: -
Hints
Editorial & Approach
Problem Overview & Intuition
To solve "REPLACE Function", we query the relational database engine using declarative SQL. The goal is to replace all occurrences of "hr" with "human resources" in the `department` column. 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: Ensure columns match the expected project schema in order.
Optimal Implementation (SQL)
SELECT name, REPLACE(department, 'HR', 'Human Resources') AS department FROM employees;Complexity Analysis
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.