I have a table with duplicate skus.
skua
skua
skub
skub
skub
skuc
skuc
skud
SELECT sku, COUNT(1) AS `Count` FROM products GROUP BY sku;
shows me all the skus that have duplicates and the number of duplicates
skua 2
skub 3
skuc 2
skud 1
I am trying to find how many there are with 2 duplicates, 3 duplicates etc.
i.e.
duplicated count
1 1 (skud)
2 2 (skua, and skuc)
3 1 (skub)
and I don't know how to write the sql. I imagine it needs a subselect...
thanks
Just use your current query as an inline view, and use the rows from that just like it was from a table.
e.g.
SELECT t.Count AS `duplicated`
, COUNT(1) AS `count`
FROM ( SELECT sku, COUNT(1) AS `Count` FROM products GROUP BY sku ) t
GROUP BY t.Count
MySQL refers to an inline view as a "derived table", and that name makes sense, when we understand how MySQL actually processes that. MySQL runs that inner query, and creates a temporary MyISAM table; once that is done, MySQL runs the outer query, using the temporary MyISAM table. (You'll see that if you run an EXPLAIN on the query.)
Above, I left your query just as you formatted it; I'd tend to reformat your query, so that entire query looks like this:
SELECT t.Count AS `duplicated'
, COUNT(1) AS `count`
FROM ( SELECT p.sku
, COUNT(1) AS `Count`
FROM products p
GROUP BY p.sku
) t
GROUP BY t.Count
(Just makes it easier for me to see the inner query, and easier to extract it and run it separately. And qualifying all column references (with a table alias or table name) is a best practice.)
select dup_count as duplicated,
count(*) as `count`,
group_concat(sku) as skus
from
(
SELECT sku, COUNT(1) AS dup_count
FROM products
GROUP BY sku
) tmp_tbl
group by dup_count
Related
I want to select all the matching results in a database table with also random results but with the matching results being at the top. With the way, I am doing now I am using two queries first one being the matching query, and if the count is zero I now select random results. I would like to do this with just one query.
You could attempt using a UNION ALL query as follows.
select product_name,price
from marketing_table
where price >=5000 /*user supplied filter*/
and price <=10000 /*user supplied filter*/
union all
select m.product_name,m.price
from marketing_table m
where not exists (select *
from marketing_table m1
where m1.price >=5000 /*user supplied filter*/
and m1.price <=10000 /*user supplied filter*/
)
What I understand from you comment, you may try something simple like this first:
SET #product := 'purse'; -- search term
SELECT * FROM product
ORDER BY product_name LIKE CONCAT('%',#product,'%') DESC, price ASC;
This is the simplest I can think of and it could be a starting point for you.
Here's a demo : https://www.db-fiddle.com/f/31jrR27dFJqYQQigzBqLcs/2
If this is not what you want, you have to edit your question and insert some example data with expected output. Your current question tend to be flagged as too broad and need focus/clarity.
Did you try using a UNION subquery with a LIMIT?
SELECT *
FROM (
SELECT 0 priority, t.*
FROM first_table t
UNION ALL
SELECT 1 priority, t.*
FROM second_table t
)
ORDER BY priority
LIMIT 20
If you do not want to include any second_table records if first_table returns, you would need to do a subquery on the second query to confirm that no rows exist.
SELECT *
FROM (
SELECT 0 priority, t.*
FROM first_table t
UNION ALL
SELECT 1 priority, t.*
FROM second_table t
LEFT JOIN (SELECT ... FROM first_table) a
WHERE a.id IS NULL
)
ORDER BY priority
LIMIT 20
I think it would be possible to use the Common Table Expressions (CTE) feature in MySQL 8, if you are using that version.
https://dev.mysql.com/doc/refman/8.0/en/with.html
I am struggling with a MySQL query which I cant get to work as I want.
In table1 I have co_id, name, code, product, logindate.
in table2 I have pr_id, productname, productno, price.
I want to count and group the PRODUCT from table1, so I can see how many that have picked for example product 1,2,3 etc.
But when I list the result on the page I will need productname, and productno for each id number in the GROUP search. table1.product is joined with table2.pr_id
This is what I have so far, but I think I am missing something with INNER JOIN or similar, right?
SELECT
codes.pickedgift,
products.productno,
products.productname,
COUNT(codes.pickedgift) as num
FROM
codes,
products
GROUP BY codes.pickedgift
ORDER BY codes.pickedgift
you missing the join condition, when you join 2 tables you should link primary key in table1 to its foreign key in another table, so your query can be:
SELECT
codes.pickedgift,
products.productno,
products.productname,
COUNT(codes.pickedgift) as num
FROM
codes INNER JOIN products ON codes.product = products.pr_id
GROUP BY codes.pickedgift
ORDER BY codes.pickedgift
You should use a sub-select for this query.
-- assuming I have your table structure correct.
SELECT p.productno, p.productname, num
FROM (SELECT codes.pickedgift, COUNT(codes.pickedgift) as num
FROM codes
GROUP BY codes.pickedgift) g
JOIN products p ON p.id = g.pickedgift
ORDER BY g.pickedgift
The other thing you have to make sure of is if you're using a group-by, the fields in your select must either be the fields in the group by, or aggregates. MySQL let's you include columns that are not part of the group-by / aggregate, it becomes ambiguous as to which value productno and productname should be represented, which is why I opted for a sub-select instead.
is there some efficient way how to write queries that join various results of GROUP BYs on a common table? How MySQL handles merging results of aggreagate functions ona a subGROUP with full fields from original table?
i am using this and its slow (and i need also other condition than CONDITION=1)
SELECT a.CID,a.AS_ALL,b.AS_ACTIVE FROM
(SELECT CID,COUNT(DISTINCT RAID) AS AS_ALL FROM MYTABLE GROUP BY CID) a
LEFT JOIN
(SELECT CID,COUNT(DISTINCT RAID) AS AS_ACTIVE FROM MYTABLE WHERE CONDITION=1 GROUP BY CID ) b ON a.CID=b.CID;
also is it save to use something like?? will MySQL always correctly merge COLUMN_A with results of aggregation?
SELECT COLUMN_A COUNT(DISTINCT COLUMN_A), SUM(COLUMN_A),SUM(COLUMN_B) FROM ATABLE WHERE CONDITION=1 GROUP BY COLUMN_C
Thank you for advice
Try this:
SELECT CID,COUNT(DISTINCT RAID) AS AS_ALL,SUM(IF(CONDITION=1, 1, 0)) AS AS_ACTIVE
FROM MYTABLE GROUP BY CID
I have the following mysql query:
SELECT id, sum(views) as total_views
FROM table
WHERE id IN (1,2,3)
GROUP BY id
ORDER BY total_views ASC
If only id 1,3 are found in the database, i still want id 2 to appear, with total_views being set to 0.
Is there any way to do that? This cannot use any other table.
This query hard-codes the list of possible IDs using a sub-query consisting of unions... it then left joins this set of ids to the table containing the information to be counted.
This will preserve an ID in your results even if there are no occurrences:
SELECT ids.id, sum(views) as total_views
FROM (
SELECT 1 AS ID
UNION ALL SELECT 2 AS ID
UNION ALL SELECT 3 AS ID
) ids
LEFT JOIN table
ON table.ID = ids.ID
GROUP BY ids.id
ORDER BY total_views ASC
Alternately, if you had a numbers table, you could do the following query:
SELECT numbers.number, sum(views) as total_views
FROM
numbers
LEFT JOIN table
ON table.ID = ids.ID
WHERE numbers.number IN (1, 2, 3)
GROUP BY numbers.number
ORDER BY total_views ASC
Here's an alternative to Micheal's solution (not a bad solution, mind you -- even with "a lot" of ID's), so long as you're not querying against a cluster.
create temporary table __ids (
id int unsigned primary key
) engine=MEMORY;
insert into __ids (id) values
(1),
(2),
(3)
;
SELECT table.id, sum(views) as total_views
FROM __ids left join table using (id)
GROUP BY table.id
ORDER BY total_views ASC
And if your query becomes complex, I could even conceive of it running more efficiently this way. But, if I were you, I'd benchmark this option with Michael's ad-hoc UNION'ed table option using real data.
in #Michael's answer, if you do have a table with the ids you care about, you can use it as "ids" in place of Michael's in-line data.
Check this fiddle... http://www.sqlfiddle.com/#!2/a9392/3
Select B.ID, sum(A.views) sum from tableB B
left outer join tableA A
on B.ID = A.ID
group by A.ID
also check
http://www.sqlfiddle.com/#!2/a1bb7/1
try this
SELECT id
(CASE 1
IF EXISTS THEN views = mytable.views END
IF NOT EXIST THEN views = 0 END
CASE 2
IF EXISTS THEN views = mytable.views END
IF NOT EXIST THEN views = 0 END
CASE 3
IF EXISTS THEN views = mytable.views END
IF NOT EXIST THEN views = 0 END), sum(views) as total_views
FROM mytable
WHERE id IN (1,2,3)
GROUP BY id
ORDER BY total_views ASC
Does it have to be rows or could you pivot the data to give you one row and a column for every id?
SELECT
SUM(IF (id=1, views, 0)) views_1,
SUM(IF (id=2, views, 0)) views_2,
SUM(IF (id=3, views, 0)) views_3
FROM table
I want to make a report of all the entries in a table where one column has duplicate entries. Let's assume we have a table like this:
customer_name | some_number
Tom 1
Steve 3
Chris 4
Tim 3
...
I want to show all the records that have some_number as a duplicate. I have used a query like this to show all the duplicate records:
select customer_name, some_number from table where some_number in (select some_number from table group by some_number having count(*) > 1) order by some_number;
This works for a small table, but the one I actually need to operate on is fairly large. 30,000 + rows and it is taking FOREVER! Does someone have a better way to do this?
Thanks!
Try this query:
SELECT t1.*
FROM (SELECT some_number, COUNT(*) AS nb
FROM your_table
GROUP BY some_number
HAVING nb>1
) t2, your_table t1
WHERE t1.some_number=t2.some_number
The query first uses GROUP BY to find duplicate records, then joins with the table to retrieve all fields.
Since HAVING is used, it will return only the records you are interested in, then do the join with your_table.
Be sure your table has an index on some_number if you want the query to be fast.
Does this perform better? It joins on a table of some_number counts and then filters to include only those with a count > 1.
SELECT t.customer_name, t.some_number
FROM my_table t
INNER JOIN (
SELECT some_number, COUNT(*) AS ct
FROM my_table
GROUP BY some_number ) dup ON t.some_number = dup.some_number
WHERE dup.ct > 1