The Problem

Table: Tweets

The tweet_id is the primary key for this table, which contains all the tweets in a social media app.

The task is to write an SQL query to find the IDs of the invalid tweets. A tweet is invalid if the number of characters used in the content of the tweet is strictly greater than 15.

Here's an example to better illustrate the problem:

Input

Tweets table:

Output

Explanation

Tweet 1 has a length of 14. It's a valid tweet.
Tweet 2 has a length of 32. It's an invalid tweet.

The Solution

In this post, we'll delve into two MSSQL solutions. Both effectively solve the problem but using different functions — highlighting their unique strengths, weaknesses, and performance metrics.

Source Code 1

The first solution uses the LEN function to calculate the length of the tweet content:

SELECT tweet_id
FROM Tweets
WHERE LEN(content) > 15

This code's runtime is 1953ms, beating 19.62% of other submissions. Here's the performance snapshot:

Source Code 2

The second solution differs from the first by using the DATALENGTH function instead of LEN:

SELECT tweet_id
FROM Tweets
WHERE DATALENGTH(content) > 15

This solution's runtime is 1522ms, beating 66.57% of other submissions. Here's the performance snapshot:

Conclusion

These two solutions effectively determine the invalid tweets based on the content length, with the second solution performing significantly better on LeetCode. However, performance may vary in real-world RDMS due to different factors, such as data volume, system hardware, SQL server configurations, etc.

Here's a ranking of these solutions based on LeetCode performance:

1. Source Code 2
2. Source Code 1

You can find the original problem at LeetCode.

For more insightful solutions and tech-related content, feel free to connect with me on my Beacons page.

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