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SQL

Find the user with the name "Alice" from the `users` table.

Problem Statement

<p>Find the user with the name "Alice" from the <code>users</code> table.</p>

Examples

Input: users table: +----+---------+-----+ | id | name | age | +----+---------+-----+ | 1 | Alice | 30 | | 2 | Bob | 25 | | 3 | Charlie | 30 | +----+---------+-----+

Output: +----+-------+-----+ | id | name | age | +----+-------+-----+ | 1 | Alice | 30 | +----+-------+-----+

Explanation: Only records matching the specified criteria are returned in the final result.

Complexity

Time Complexity: -

Space Complexity: -

Hints

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

Editorial & Approach

Problem Overview & Intuition

To solve "Filter by Equality", we query the relational database engine using declarative SQL. The goal is to find the user with the name "alice" 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

  1. Analyze Schema: Identify the target tables, necessary foreign keys, and expected output columns.
  2. Construct Filtering & Logic: Apply WHERE filtering to isolate the requested data.
  3. Format & Order: Ensure columns match the expected project schema in order.

Optimal Implementation (SQL)

SELECT * FROM users WHERE name = 'Alice';

Complexity Analysis

Time Complexity O(N) full table scan or O(log N) if filtered column is indexed.
Space Complexity O(K) where K is the number of filtered rows returned.

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.

Filter by Equality

Easy

Find the user with the name "Alice" from the users table.

Example Scenarios
1Example 1
Input:
users table
idnameage
1Alice30
2Bob25
3Charlie30
Output:
idnameage
1Alice30
Explanation:

Only records matching the specified criteria are returned in the final result.

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