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Hard
Database

3368. First Letter Capitalization 🔒

中文文档

Description

Table: user_content

+-------------+---------+
| Column Name | Type    |
+-------------+---------+
| content_id  | int     |
| content_text| varchar |
+-------------+---------+
content_id is the unique key for this table.
Each row contains a unique ID and the corresponding text content.

Write a solution to transform the text in the content_text column by applying the following rules:

  • Convert the first letter of each word to uppercase
  • Keep all other letters in lowercase
  • Preserve all existing spaces

Note: There will be no special character in content_text.

Return the result table that includes both the original content_text and the modified text where each word starts with a capital letter.

The result format is in the following example.

 

Example:

Input:

user_content table:

+------------+-----------------------------------+
| content_id | content_text                      |
+------------+-----------------------------------+
| 1          | hello world of SQL                |
| 2          | the QUICK brown fox               |
| 3          | data science AND machine learning |
| 4          | TOP rated programming BOOKS       |
+------------+-----------------------------------+

Output:

+------------+-----------------------------------+-----------------------------------+
| content_id | original_text                     | converted_text                    |
+------------+-----------------------------------+-----------------------------------+
| 1          | hello world of SQL                | Hello World Of Sql                |
| 2          | the QUICK brown fox               | The Quick Brown Fox               |
| 3          | data science AND machine learning | Data Science And Machine Learning |
| 4          | TOP rated programming BOOKS       | Top Rated Programming Books       |
+------------+-----------------------------------+-----------------------------------+

Explanation:

  • For content_id = 1:
    • Each word's first letter is capitalized: Hello World Of Sql
  • For content_id = 2:
    • Original mixed-case text is transformed to title case: The Quick Brown Fox
  • For content_id = 3:
    • The word AND is converted to "And": "Data Science And Machine Learning"
  • For content_id = 4:
    • Handles word TOP rated correctly: Top Rated
    • Converts BOOKS from all caps to title case: Books

Solutions

Solution 1

MySQL

WITH RECURSIVE
    capitalized_words AS (
        SELECT
            content_id,
            content_text,
            SUBSTRING_INDEX(content_text, ' ', 1) AS word,
            SUBSTRING(
                content_text,
                LENGTH(SUBSTRING_INDEX(content_text, ' ', 1)) + 2
            ) AS remaining_text,
            CONCAT(
                UPPER(LEFT(SUBSTRING_INDEX(content_text, ' ', 1), 1)),
                LOWER(SUBSTRING(SUBSTRING_INDEX(content_text, ' ', 1), 2))
            ) AS processed_word
        FROM user_content
        UNION ALL
        SELECT
            c.content_id,
            c.content_text,
            SUBSTRING_INDEX(c.remaining_text, ' ', 1),
            SUBSTRING(c.remaining_text, LENGTH(SUBSTRING_INDEX(c.remaining_text, ' ', 1)) + 2),
            CONCAT(
                c.processed_word,
                ' ',
                CONCAT(
                    UPPER(LEFT(SUBSTRING_INDEX(c.remaining_text, ' ', 1), 1)),
                    LOWER(SUBSTRING(SUBSTRING_INDEX(c.remaining_text, ' ', 1), 2))
                )
            )
        FROM capitalized_words c
        WHERE c.remaining_text != ''
    )
SELECT
    content_id,
    content_text AS original_text,
    MAX(processed_word) AS converted_text
FROM capitalized_words
GROUP BY 1, 2;

Pandas

import pandas as pd


def process_text(user_content: pd.DataFrame) -> pd.DataFrame:
    user_content["converted_text"] = user_content["content_text"].apply(
        lambda text: " ".join(word.capitalize() for word in text.split(" "))
    )
    return user_content[["content_id", "content_text", "converted_text"]].rename(
        columns={"content_text": "original_text"}
    )