Question

1683. Invalid Tweets

中文文档

Description

Table: Tweets

+----------------+---------+
| Column Name  | Type  |
+----------------+---------+
| tweet_id     | int   |
| content    | varchar |
+----------------+---------+
tweet_id is the primary key (column with unique values) for this table.
This table contains all the tweets in a social media app.

 

Write a solution to find the IDs of the invalid tweets. The tweet is invalid if the number of characters used in the content of the tweet is strictly greater than 15.

Return the result table in any order.

The result format is in the following example.

 

Example 1:

Input: 
Tweets table:
+----------+----------------------------------+
| tweet_id | content              |
+----------+----------------------------------+
| 1    | Vote for Biden           |
| 2    | Let us make America great again! |
+----------+----------------------------------+
Output: 
+----------+
| tweet_id |
+----------+
| 2    |
+----------+
Explanation: 
Tweet 1 has length = 14. It is a valid tweet.
Tweet 2 has length = 32. It is an invalid tweet.

Solutions

Solution 1: Using CHAR_LENGTH Function

The CHAR_LENGTH() function returns the length of a string, where Chinese characters, numbers, and letters are all counted as $1$ byte.

The LENGTH() function returns the length of a string, where under utf8 encoding, Chinese characters are counted as $3$ bytes, while numbers and letters are counted as $1$ byte; under gbk encoding, Chinese characters are counted as $2$ bytes, while numbers and letters are counted as $1$ byte.

For this problem, we can directly use the CHAR_LENGTH function to get the length of the string, and filter out the tweet IDs with a length greater than $15$.

# Write your MySQL query statement below
SELECT
  tweet_id
FROM Tweets
WHERE CHAR_LENGTH(content) > 15;