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SQL Count(*) on multiple tables

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sql

count

I am writing a horse racing web app and i have a stats page. What i am trying to do is show how many winners there are from each year.

Currently i have this:

SELECT `Horse Number`, Count(*) AS `Total Winners`
FROM `races`.`2009`
WHERE `Win $`>0 
GROUP BY `Horse Number`
ORDER BY Count(*) DESC;

It works like a charm and returns the following

Horse Number | Total Winners
1|48
2|49
3|39
4|31
5|26
6|31
7|21
8|25
9|31
10|16
11|16
12|20
13|9
14|8
15|6
16|3
17|3
18|2
19|2

I have now created a table for 2010 and i am wanting SQL to return something similar but i want it to search over 2009 and 2010 at the same time. I thought something like this might do the trick.

SELECT `Horse Number`, Count(*) AS `Total Winners`
FROM `races`.`2009`
WHERE `Win $`>0 
GROUP BY `Horse Number`
UNION
SELECT `Horse Number`, Count(*) AS `Total Winners`
FROM `races`.`2010`
WHERE `Win $`>0 
GROUP BY `Horse Number`
ORDER BY Count(*) DESC;

But it is just returning extra results at the bottom of the table so i now have 2 rows for each horse like this

Horse Number | Total Winners
1|48
2|49
3|39
4|31
5|26
6|31
7|21
8|25
9|31
10|16
11|16
12|20
13|9
14|8
15|6
16|3
17|3
18|2
19|2
1|0
2|0
3|0
4|0
5|0
6|0
7|0
8|0
9|0
10|0
11|0
12|0
13|0
14|0
15|0
16|0
17|0
18|0
19|0

Is anyone able to assist me please

Thanks

like image 431
Glen Avatar asked Jan 01 '10 08:01

Glen


People also ask

How do I COUNT multiple tables in SQL?

To achieve this for multiple tables, use the UNION ALL. select sum(variableName. aliasName) from ( select count(*) as yourAliasName from yourTableName1 UNION ALL select count(*) as yourAliasName from yourTableName2 ) yourVariableName; Let us implement the above syntax.

What does COUNT (*) do in SQL?

COUNT(*) returns the number of rows in a specified table, and it preserves duplicate rows. It counts each row separately. This includes rows that contain null values.

Which is faster COUNT (*) or COUNT column?

The simple answer is no – there is no difference at all. The COUNT(*) function counts the total rows in the table, including the NULL values.


1 Answers

First off, I would suggest having ONE table with an extra column for a year.

Second, with the current table structure, you can do

SELECT `Horse Number`, Count(*) AS `Total Winners`
FROM (
  SELECT * FROM `races`.`2009`
  UNION ALL
  SELECT * FROM `races`.`2010`
) all_races
WHERE `Win $`>0 
GROUP BY `Horse Number`
ORDER BY Count(*) DESC;
like image 110
DVK Avatar answered Sep 18 '22 22:09

DVK