Question

I’m using JOIN with MySQL to select an article and all comments related to it, but I realized that when I select an article and there’s more than one comment for it, I get the same article duplicated by the number of comments. For example:
I have the table articles with the following columns:
1. id
2. article
And the table comments with the following columns:
1. c_id
2. body
3. a_id

MySQL query I tried to use:

SELECT  * FROM `articles`
JOIN`comments`
ON (`articles`.id = `comments`.a_id)
WHERE `articles`.id = 134  

And this is the final result:

id  article   c_id  body        a_id
134 Article1    2   Comment1    134
134 Article1    3   Comment2    134
134 Article1    8   Comment3    134  

So my question is: Since I’m getting the same article column’s value for every comment,
does this slows the MySQL query or my web application by anyway? since I’m requesting more data then what I really need.
I can separate the query to 2 simple SELECT queries, but this will be overkill, right?

Thanks for reading.

Edit:
What if I the article column’s value is bigger, something that contains 1k+ characters, will it make since to duplicate it?

Answer 1

Since I’m getting the same article column’s value for every comment,
does this slows the MySQL query or my web application by anyway? since
I’m requesting more data then what I really need.

Since the database is transmitting more bytes than it needs to there is performance cost associated with this but it may not be noticeable.

I can separate the query to 2 simple SELECT queries, but this will be overkill, right?

Its hard to say without measuring. If the value of article was a Gigabyte instead of a few characters then you would probably want to do two selects instead of one.