I am very new to Microsoft reporting. I have the following table in my database:
CategoryName Id
Normal 1
High 2
Normal 3
Low 4
Normal 5
Normal 6
Normal 7
Normal 8
Low 9
Low 10
Low 11
High 12
I want to group by Category and also show the count of each category. Here is what I did:
I inserted a two column table and I grouped by the categoryName in the first column and in the second column, I tried doing
=CountDistinct(Fields!CategoryName.Value)
This is what I am seeing in the report
High 1
1
Normal 1
1
1
1
1
1
1
Low 1
1
1
1
I want to see something like this:
Category Count
Normal 6
Low 4
High 2
any help will be highly appreciated
Delete the Detail row and put the Count epxression in the Group row.
You'd probably be better off doing this in the query. Easier and leaves less room for error. Something like the following should work.
SELECT categoryName, COUNT(*)
FROM your table
GROUP BY categoryName
Related
I have 1 table from which I return search results and display them in a a specific order. This example is an exact, simplified version of my db structure: http://www.java2s.com/Code/SQL/Select-Clause/Orderbyvaluefromsubquery.htm
and here is my current code, which works but heavily impacts performance to a large extend because of the subquery used:
SELECT * FROM `table` AS p1
WHERE CONCAT(title,artist,creator,version) LIKE '%searchInput%'
ORDER BY
(SELECT
MAX(`rating`) FROM `table` AS p2 WHERE p1.setId=p2.setId
) DESC
the above code searches and sorts the result sets by the highest rating in the set and that all rows from the same set are kept together, for example:
id setId rating title,artist,etc...
1 1 5
2 1 5
3 2 7
4 1 6
5 2 1
6 3 3
would sort to:
id setId rating title,artist,etc...
3 2 7
5 2 1
4 1 6
1 1 5
2 1 5
6 3 3
Currently it takes around 8.5sec to query 1000 rows and over half a minute for a large amount of rows, is there any way to improve the performance or would it be better to fetch all the results and sort them in PHP memory?
Help is much appreciated
You can probably speed things up a bit by separating the LIKEs:
SELECT p1.* FROM `table` AS p1
WHERE (title LIKE '%searchInput%')
OR (artist LIKE '%searchInput%')
OR (creator LIKE '%searchInput%')
OR (version LIKE '%searchInput%')
ORDER BY
(SELECT MAX(`rating`) FROM `table` AS p2 WHERE p1.setId=p2.setId) DESC
You could also try to
CREATE INDEX tbl_ndx ON table(setId, rating)
to improve sorting performances.
Have a existing table of results like this;
race_id race_num racer_id place
1 0 32 2
1 1 32 3
1 2 32 1
1 3 32 6
1 0 44 2
1 1 44 2
1 2 44 2
1 3 44 2
etc...
Have lots of PHP scripts that access this table output the results in a nice format.
Now I have a case where I need to output the results for only certain race_nums.
So I have created this table races_included.
race_view race_id race_num
Day 1 1 0
Day 1 1 1
Day 2 1 2
Day 2 1 3
And can use this query to get the right results.
SELECT racer_id, place from results WHERE race_id=1
AND race_num IN
(SELECT race_num FROM races_included WHERE race_id='1' AND race_view='Day 1')
This is great but I only need this feature for a few races and to have it work in a compatible mode for the simple case show all races. I need to add alot of rows to the races_included table. Like
race_view race_id race_num
All 1 0
All 1 1
All 1 2
All 1 3
95% of my races don't use the daily feature.
So I am looking for a way to change the query so that if for race 1 there are no records in the races_included table it defaults to all races. In addition I need it to be close the same execution speed as the query without the IN clause, because this query Or variations of it are used a lot.
One way that does work is to redefine the table as races_excluded and use NOT IN. This works great but is a pain to manage the table when races are added or deleted.
Is there a simple way to use EXISTS and IN in tandem as a subquery to get the desired results? Or some other neat trick I am missing.
To clarify I have found a working but very slow solution.
SELECT * FROM race_results WHERE race_id=1
AND FIND_IN_SET(race_num, (SELECT IF((SELECT Count(*) FROM races_excluded
WHERE rid=1>0),(SELECT GROUP_CONCAT(rnum) FROM races_excluded
WHERE rid=1 AND race_view='Day 1' GROUP BY rid),race_num)))
It basically checks if any records exists for that race_id and if not return a set equal to the current race_num and if yes returns a list of included race nums.
You can do this by using or in the subquery:
SELECT racer_id, plac
from results
WHERE race_id = 1 AND
race_num IN (SELECT race_num
FROM races_included
WHERE race_id = '1' AND (race_view = 'Day 1' or raw_view = 'ANY')
);
I have table like this:
id products
------ ----------
5 1,2,3
6 2,4,5
9 1,4,7
17 4,6,7
18 1,6,8
19 2,3,6
I have to select only that rows, which row's products column contains one of (2,3) values.
In this case query must return:
id products
------ ----------
5 1,2,3
6 2,4,5
19 2,3,6
But I don't understand how to make construction of this query.
Any ideas?
Thanks in advance.
SELECT id,products
FROM yourTable
WHERE FIND_IN_SET('2',products)>0
OR FIND_IN_SET('3',products)>0
sqlFiddle
Would you mind to try this one please?
select * from TABLE_NAME where products regexp "(^|,)[23](,|$)";
Its doing either two or three at the begining, or at end. Or in between the commas.
Never, never, never store multiple values in one column.
Like you see now this will only give you headaches. Normalize your table. Then you can select normally.
Your table should look like this
id product
-- -------
5 1
5 2
5 3
6 2
6 4
6 5
...
With that table structure your select would be
select id
from your_normalized_table
where product in (2,3)
group by id
having count(distinct product) = 2
That query can make use of indexes and is really fast.
I found it hard to find a fitting title. For simplicity let's say I have the following table:
cook_id cook_rating
1 2
1 1
1 3
1 4
1 2
1 2
1 1
1 3
1 5
1 4
2 5
2 2
Now I would like to get an output of 'good' cooks. A good cook is someone who has a rating of at least 70% of 1, 2 or 3, but not 4 or 5.
So in my example table, the cook with id 1 has a total of 10 ratings, 7 of which have type 1, 2 and 3. Only three have type 4 or 5. Therefore the cook with id 1 would be a 'good' cook, and the output should be the cook's id with the number of good ratings.
cook_id cook_rating
1 7
The cook with id 2, however, doesn't satisfy my condition, therefore should not be listed at all.
select cook_id, count(cook_rating) - sum(case when cook_rating = 4 OR cook_rating = 5 then 1 else 0 end) as numberOfGoodRatings from cook
where cook_rating in (1,2,3,4,5)
group by cook_id
order by numberOfGoodRatings desc
However, this doesn't take into account the fact that there might be more 4 or 5 than good ratings, resulting in negative outputs. Plus, the requirement of at least 70% is not included.
You can get this with a comparison in your HAVING clause. If you must have just the two columns in the result set, this can be wrapped as a sub-select select cook_id, positive_ratings FROM (...)
SELECT
cook_id,
count(cook_rating < 4 OR cook_rating IS NULL) as positive_ratings,
count(*) as total_ratings
FROM cook
GROUP BY cook_id
HAVING (positive_ratings / total_ratings) >= 0.70
ORDER BY positive_ratings DESC
Edit Note that count(cook_rating < 4) is intended to only count rows where the rating is less than 4. The MySQL documentation says that count will only count non-null rows. I haven't tested this to see if it equates FALSE with NULL but I would be surprised it it doesn't. Worst case scenario we would need to wrap that in an IF(cook_rating < 4, 1,NULL).
I suggest you change a little your schema to make this kind of queries trivial.
Suppose you add 5 columns to your cook table, to simply count the number of each ratings :
nb_ratings_1 nb_ratings_2 nb_ratings_3 nb_ratings_4 nb_ratings_5
Updating such a table when a new rating is entered in DB is trivial, just as would be recomputing those numbers if having redundancy makes you nervous. And it makes all filterings and sortings fast and easy.
I appreciate that this may appear to many as a dum question but I cannot find a clear explanation anywhere as to what the effect of "group by" has on a select max(...) from SQL statement.
I have the following data (there is another column image of type mediumblob which is not shown):
id title test_id
1 bomb 0
2 Soft watch 2
3 Dali 1
4 Narciss 1
5 The Woman In Green 0
6 A summer in Vetheuil 0
7 Artist's Garden 2
8 Beech Forest 2
9 Claude Monet 0
I know if I perform
select max(id) from images
where image is not null;
I get the max value of id i.e.:
max(id)
9
However can someone please explain what is happening when I perform
select max(id), title, test_id
from images
where image is not null
group by id;
I find that the max(id) serves no useful purpose (results shown below)?
max(id) title test_id
1 bomb 0
2 Soft watch 2
3 Dali 1
4 Narciss 1
5 The Woman In Green 0
6 A summer in Vetheuil 0
7 Artist's Garden 2
8 Beech Forest 2
9 Claude Monet 0
In the case of using MAX() the GROUP BY clause essentially tells the query engine how to group the items from which to determine a maximum. In your first example you were selecting only a single column, so there was no need for grouping. But in your second example you had multiple columns. So you need to tell the query engine how to determine which ones are going to be compared to find a maximum.
You told it to group by the id column. Which means that it's going to compare records which have the same id and give you the maximum one for each unique id. Since every record has a different id, you essentially didn't do anything with that clause.
It grouped all records with an id of 1 (which was a single record), and returned the record with the maximum id from that group (which was that record). It did the same for 2, 3, etc.
In the case of the three columns shown here, the only place where it would make sense to group your records would be on the test_id column. Something like this:
SELECT MAX(id), title, test_id
FROM images
WHERE image IS NOT null
GROUP BY test_id
This would group them by the test_id, so the results will include records 6 (the maximum id for test_id 0), 4 (the maximum id for test_id 1), and 8 (the maximum id for test_id 2). By splitting the records into those three groups based on the three unique values in the test_id column, it can effectively find a "maximum" id within each group.
Yes, in your example it serves no useful purpose.
You're grouping by ID then finding the maximum ID. But that doesn't make sense since there's only one of each ID. Normally MAX() is used on quantities, like prices or item counts or such like.
Group by is not used for this kind of queries
Its is used for queries like this
OId OrderDate OrderPrice Customer
1 2008/11/12 1000 Hansen
2 2008/10/23 1600 Nilsen
3 2008/09/02 700 Hansen
4 2008/09/03 300 Hansen
5 2008/08/30 2000 Jensen
6 2008/10/04 100 Nilsen
Now if you want to get sum of material bought by each customer of these you will use group by
SELECT Customer,SUM(OrderPrice) FROM Orders
GROUP BY Customer
customer SUM(OrderPrice)
Hansen 2000
Nilsen 1700
Jensen 2000
In above case id is unique so group by id will not make any sense