Question

I have different tables in my MYSQL database and I need to create a SELECT query that will check certain values before selecting a row.

It’s basically 3 tables (news, tags and news_tags).

1. news contains information about a news.
2. tags information about tags.
3. news_tags store which tag is used by a news.

Here are my 3 different tables (simplified of course)

To illustrate:

news:

id | status
1  | 1
2  | 1
3  | 0

tags:

tag_id | tag_name
1      | name 1 
2      | name 2

news_tags:

id | news_id | tag_id
1  | 1       | 1
2  | 1       | 2
3  | 2       | 1
4  | 3       | 1
5  | 3       | 2

Now, at first I wanted to know how many times each tag was being used.
So I came up with this query

SELECT tags.tag_name, news_tags.tag_id, COUNT(*) as count 
FROM news_tags 
LEFT JOIN tags 
ON tags.tag_id = news_tags.tag_id 
GROUP BY news_tags.tag_id 
ORDER BY count DESC

This give me the following output

tag_name | count
name 1   | 3 
name 2   | 2

Now my problem is that I don’t want to count those that the news.status = 0;
So if we look at my example, in the news table the row with the id = 3 has a status = 0.
The count should not take in effect where news_id = 3 in the news_tags table.

Basically the desired output should be

tag_name | count
name 1   | 2 
name 2   | 1

Thank you for your help.

Answer 1

You need to join it with news table so you can query for status

SELECT tags.tag_name, news_tags.tag_id, COUNT(*) as count 
FROM    news_tags 
        LEFT JOIN tags 
            ON tags.tag_id = news_tags.tag_id 
        LEFT JOIN news
            ON news.id = news_tags.news_id
WHERE   news.status = 1
GROUP BY news_tags.tag_id 
ORDER BY count DESC