Help to write SQL query

Question

Hi all,

I have 2 tables as follows:

tags:
    id
    version
    name

tag_links:
    id
    version
    tag_id (foreign key to tags.id)

I need to write an SQL statement that returns how many times each tag_id occurs in tag_links table.

For example:

tags:
    id  version  name
    --  -------  ------
     1        1  sport
     2        1  comedy

tag_links:
    id  version  tag_id
    --  -------  ------
     1        1       1
     2        1       1
     3        1       1
     4        1       2
     5        1       2

The result I need is:

tag_id  times_occurred
------  --------------
     1               3
     2               2

I have a little knowledge of SQL and I tried to write it but :(

Thank you.

Answer 1

SELECT tag_id, COUNT(*) AS times_occurred
FROM tag_links
GROUP BY tag_id

Answer 2

You don't even need to join tables for this one since all the info you want is in the tag_links table.

select tag_id, count(*) as times_occurred
from tag_links
group by tag_id;

If you wanted the tag names, you'd need to join the tables but that doesn't appear to be the case here.

Answer 3

select id,count(*)  from tags inner join tag_links on tags.tag_id = tag_links.tag_id
group by id

Answer 4

SELECT   tag_id, 
         Count(*) As times_occurred
FROM     tag_links
GROUP BY tag_id