Select user names as `full_name` and age as `years_old` from the `users` table.

Problem Statement

<p>Select user names as <code>full_name</code> and age as <code>years_old</code> from the <code>users</code> table.</p>

Examples

Input: users table: +----+-------+-----+ | id | name | age | +----+-------+-----+ | 1 | Alice | 30 | | 2 | Bob | 25 | +----+-------+-----+

Output: +-----------+-----------+ | full_name | years_old | +-----------+-----------+ | Alice | 30 | | Bob | 25 | +-----------+-----------+

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

Complexity

Time Complexity: -

Space Complexity: -

Hints

💡 Hint 1: Carefully review the required fields in the table schema. 💡 Hint 2: Construct a clean SELECT statement specifying the requested columns or wildcard *. 💡 Hint 3: Structure: SELECT <columns> FROM <table_name>;

Editorial & Approach

Problem Overview & Intuition

To solve "Column Aliasing (AS)", we query the relational database engine using declarative SQL. The goal is to select user names as `full_name` and age as `years_old` from the `users` 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: Ensure columns match the expected project schema in order.

Optimal Implementation (SQL)

SELECT name AS full_name, age AS years_old 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.

Column Aliasing (AS)

Easy

Select user names as full_name and age as years_old from the users table.

Example Scenarios

1Example 1

Input:

users table

id	name	age
1	Alice	30
2	Bob	25

Output:

full_name	years_old
Alice	30
Bob	25

Explanation:

The query retrieves the requested records satisfying all problem requirements.

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