Is Convert Date Format easy or hard?

Convert Date Format is considered an Easy database problem with a high acceptance rate. The challenge mainly checks whether you know MySQL’s DATE_FORMAT() function and the correct format specifiers to display weekday, month name, day, and year.

Convert Date Format Python/Java solution

This problem is categorized under SQL database queries, so the primary solution is written in MySQL. If implemented in application code like Python or Java, you would parse the date using standard libraries such as datetime or SimpleDateFormat and then format it into the desired string pattern.

How to solve Convert Date Format in O(n)?

Use a SELECT query that applies the MySQL DATE_FORMAT() function to the date column. The database engine formats each row during the scan, producing strings like 'Wednesday, January 01, 2020'. Because every row is processed exactly once, the complexity remains O(n).

What is the best approach for Convert Date Format?

The best approach uses MySQL’s DATE_FORMAT() function to transform the date directly inside the query. It converts parts of a date such as weekday, month, day, and year using format specifiers like %W, %M, %d, and %Y. This solution runs in O(n) time since each row is formatted once and requires O(1) extra space.

Is Convert Date Format asked at Google/Amazon/Meta?

Database formatting questions appear frequently in SQL interview rounds at companies such as Amazon, Google, and Meta. While this exact problem may vary, candidates are often tested on SQL date functions, formatting, and built‑in utilities like DATE_FORMAT or TO_CHAR.

What data structure is used in Convert Date Format?

No specialized data structure is required. The solution relies on SQL date functions operating directly on table rows. The database engine reads each record and applies DATE_FORMAT() to produce the formatted string.

What is the time complexity of Convert Date Format?

The query performs a single scan over the Days table. Each row applies the DATE_FORMAT() function once, so the total time complexity is O(n) where n is the number of rows. No additional memory structures are created, giving O(1) space complexity.

Description Solution Video 3:41

1853. Convert Date Format

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Table: Days

+-------------+------+
| Column Name | Type |
+-------------+------+
| day         | date |
+-------------+------+
day is the column with unique values for this table.

Write a solution to convert each date in Days into a string formatted as "day_name, month_name day, year".

Return the result table in any order.

The result format is in the following example.

Example 1:

Input: 
Days table:
+------------+
| day        |
+------------+
| 2022-04-12 |
| 2021-08-09 |
| 2020-06-26 |
+------------+
Output: 
+-------------------------+
| day                     |
+-------------------------+
| Tuesday, April 12, 2022 |
| Monday, August 9, 2021  |
| Friday, June 26, 2020   |
+-------------------------+
Explanation: Please note that the output is case-sensitive.

Topics

Database

3:41

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Case 1

Input

{"headers":{"Days":["day"]},"rows":{"Days":[["2022-04-12"],["2021-08-09"],["2020-06-26"]]}}

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