Select name, and a "type" column that is "Senior" if age > 35 else "Junior".

Problem Statement

<p>Select name, and a "type" column that is "Senior" if age > 35 else "Junior".</p>

Examples

Input: users table: +----+-------+-----+ | id | name | age | +----+-------+-----+ | 1 | Alice | 30 | | 2 | Bob | 40 | +----+-------+-----+

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

Complexity

Time Complexity: -

Space Complexity: -

Hints

💡 Hint 1: Use a conditional CASE WHEN ... THEN ... ELSE ... END expression to transform values or implement if-else logic. 💡 Hint 2: Each condition is evaluated in order; provide a sensible ELSE fallback if unhandled cases exist. 💡 Hint 3: Place the CASE expression in the SELECT list with an alias: SELECT CASE WHEN condition THEN val ELSE default END AS column_name FROM ...;

Editorial & Approach

Problem Overview & Intuition

To solve "Basic CASE Statement", we query the relational database engine using declarative SQL. The goal is to select name, and a "type" column that is "senior" if age > 35 else "junior". 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, CASE WHEN age > 35 THEN 'Senior' ELSE 'Junior' END AS type FROM users;

Complexity Analysis

Time Complexity O(N)

Space Complexity O(1)

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.

Basic CASE Statement

Medium

Select name, and a "type" column that is "Senior" if age > 35 else "Junior".

Example Scenarios

1Example 1

Input:

users table

id	name	age
1	Alice	30
2	Bob	40

Output:

name	type
Alice	Junior
Bob	Senior

Explanation:

The query retrieves the requested records satisfying all problem requirements.

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