SQL COUNT records in table 2 JOINS away

Posted by Fred K on Stack Overflow See other posts from Stack Overflow or by Fred K
Published on 2010-04-08T08:01:25Z Indexed on 2010/04/08 8:13 UTC
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mysql

|

sql

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select

|

join

|

count

Using MySQL, I have three tables:

projects:

ID  name
1   "birthday party"
2   "soccer match"
3   "wine tasting evening"
4   "dig out garden"
5   "mountainbiking"
6   "making music"

batches:

ID  projectID  templateID  when
1   1          1            7 days before
2   1          1            1 day  before
3   4          2           21 days before
4   4          1            7 days before
5   5          1            7 days before
6   3          5            7 days before
7   3          3           14 days before
8   5          1           14 days before

templates:

ID  message
1   "Hi, I'd like to invite ..."
2   "Dear Sir, Madam, ..."
3   "Can you please ..."
4   "Would you like to ..."
5   "To all dear friends ..."
6   "Does any of you guys ..."

I would like to display a table of templates and the number of projects they're used in. So, the result should be:

templateID  projectCount
1           3
2           1
3           1
4           0
5           1
6           0

I've tried all kinds of SQL queries using various JOINs, but I guess this is too complicated for me. Is it possible to get this result using a single SQL statement?

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