i wonder how to using group by but still displaying full data? i just want to group it.
here i give an example of my table :
this is my query :
(SELECT dp.menu_paket,d.id_detail,t.no_meja,m.nama_menu,d.jumlah,t.status,t.nama_pegawai
FROM menu m
join detail_paket dp on dp.menu_paket=m.nama_menu
JOIN detail_transaksi d on m.id_menu = d.id_menu
join transaksi t on t.id_transaksi=d.id_transaksi where t.status='progress' and d.status_menu='progress' group by id_detail)
UNION
(SELECT dp.menu_paket,d.id_detail,t.no_meja,p.nama_paket,d.jumlah,t.status,t.nama_pegawai
FROM paket p
join detail_paket dp on dp.id_paket=p.id_paket
JOIN detail_transaksi d on d.id_paket=p.id_paket
join transaksi t on t.id_transaksi=d.id_transaksi where t.status='progress' and d.status_menu='progress' group by id_detail);
thanks..!
You can apply distinct to avoid same multiple records instead of group by. because group by is used when there is aggregate function is your query.
Distinct retrieves single row instead of multiple rows when two rows are totally same.
Try this
select distinct columnname from table name
union
select distinct columnname1 from table name
I think I see two issues.
1) GROUP BY is generally used when you want to group rows for an aggregate function like SUM. You may be looking for ORDER BY, which controls the order of the rows. You can specify multiple columns for ORDER BY to obtain a "grouping" effect. This is what you want if you just want the rows to be next to each other in the list.
2) UNION, at least in the databases I know of, removes duplicate rows. You want UNION ALL if you want to preserve all rows.
Edit:
In response to the poster's comment, you definitely want ORDER BY and maybe UNION ALL. It should be ORDER BY no_meja, id_transaksi. Try the following query and see if it gives you what you want:
SELECT * FROM
((SELECT dp.menu_paket,d.id_detail,t.no_meja,m.nama_menu,d.jumlah,t.status,t.nama_pegawai
FROM menu m
join detail_paket dp on dp.menu_paket=m.nama_menu
JOIN detail_transaksi d on m.id_menu = d.id_menu
join transaksi t on t.id_transaksi=d.id_transaksi
where t.status='progress' and d.status_menu='progress')
UNION ALL
(SELECT dp.menu_paket,d.id_detail,t.no_meja,p.nama_paket,d.jumlah,t.status,t.nama_pegawai
FROM paket p
join detail_paket dp on dp.id_paket=p.id_paket
JOIN detail_transaksi d on d.id_paket=p.id_paket
join transaksi t on t.id_transaksi=d.id_transaksi
where t.status='progress' and d.status_menu='progress')) x
ORDER BY x.no_meja, x.id_transaksi;
Related
I am using the following query to join tables together and it seems to be working although I can't really understand why:
SELECT
listing.name,
biggestLot.price,
FROM Listings listing
LEFT JOIN Lots biggestLot ON biggestLot.lotNumber = (
SELECT lotNumber
FROM Lots
WHERE lotNumber IN
(
SELECT lotNumber
FROM Listings listingInner
WHERE listingInner.listingNumber = listing.listingNumber
)
ORDER BY size DESC
LIMIT 1
)
GROUP BY listing.listingNumber
The context is that each "Listing" is associated with one or more "Lots" through a "lotNumber" field. The tables aren't normalized; i.e. for any given Listing, there may be one or more rows in the "Listings" table that have duplicate values for all fields except for "lotNumber". The intent of the above query is to find the price of the biggest Lot associated with each Listing.
The inner SELECT is getting the largest Lot for a given Listing and I understand how that works. What I don't understand is how the LEFT JOIN merges the biggestLot result with the outer SELECT Listings query. I'm not specifying an ON field to combine the two tables so how does it know how to combine the results?
You could can use window functions along with the JOIN:
SELECT l.name, lo.price,
FROM Listings l LEFT JOIN
(SELECT lo.*,
ROW_NUMBER() OVER (PARITION BY lo.lotNumber ORDER BY lo.size DESC) as seqnum
FROM Lots lo
) lo
USING (lotNmber);
I have this query I need to optimize further since it requires too much cpu time and I can't seem to find any other way to write it more efficiently. Is there another way to write this without altering the tables?
SELECT category, b.fruit_name, u.name
, r.count_vote, r.text_c
FROM Fruits b, Customers u
, Categories c
, (SELECT * FROM
(SELECT *
FROM Reviews
ORDER BY fruit_id, count_vote DESC, r_id
) a
GROUP BY fruit_id
) r
WHERE b.fruit_id = r.fruit_id
AND u.customer_id = r.customer_id
AND category = "Fruits";
This is your query re-written with explicit joins:
SELECT
category, b.fruit_name, u.name, r.count_vote, r.text_c
FROM Fruits b
JOIN
(
SELECT * FROM
(
SELECT *
FROM Reviews
ORDER BY fruit_id, count_vote DESC, r_id
) a
GROUP BY fruit_id
) r on r.fruit_id = b.fruit_id
JOIN Customers u ON u.customer_id = r.customer_id
CROSS JOIN Categories c
WHERE c.category = 'Fruits';
(I am guessing here that the category column belongs to the categories table.)
There are some parts that look suspicious:
Why do you cross join the Categories table, when you don't even display a column of the table?
What is ORDER BY fruit_id, count_vote DESC, r_id supposed to do? Sub query results are considered unordered sets, so an ORDER BY is superfluous and can be ignored by the DBMS. What do you want to achieve here?
SELECT * FROM [ revues ] GROUP BY fruit_id is invalid. If you group by fruit_id, what count_vote and what r.text_c do you expect to get for the ID? You don't tell the DBMS (which would be something like MAX(count_vote) and MIN(r.text_c)for instance. MySQL should through an error, but silently replacescount_vote, r.text_cbyANY_VALUE(count_vote), ANY_VALUE(r.text_c)` instead. This means you get arbitrarily picked values for a fruit.
The answer hence to your question is: Don't try to speed it up, but fix it instead. (Maybe you want to place a new request showing the query and explaining what it is supposed to do, so people can help you with that.)
Your Categories table seems not joined/related to the others this produce a catesia product between all the rows
If you want distinct resut don't use group by but distint so you can avoid an unnecessary subquery
and you dont' need an order by on a subquery
SELECT category
, b.fruit_name
, u.name
, r.count_vote
, r.text_c
FROM Fruits b
INNER JOIN Customers u ON u.customer_id = r.customer_id
INNER JOIN Categories c ON ?????? /Your Categories table seems not joined/related to the others /
INNER JOIN (
SELECT distinct fruit_id, count_vote, text_c, customer_id
FROM Reviews
) r ON b.fruit_id = r.fruit_id
WHERE category = "Fruits";
for better reading you should use explicit join syntax and avoid old join syntax based on comma separated tables name and where condition
The next time you want help optimizing a query, please include the table/index structure, an indication of the cardinality of the indexes and the EXPLAIN plan for the query.
There appears to be absolutely no reason for a single sub-query here, let alone 2. Using sub-queries mostly prevents the DBMS optimizer from doing its job. So your biggest win will come from eliminating these sub-queries.
The CROSS JOIN creates a deliberate cartesian join - its also unclear if any attributes from this table are actually required for the result, if it is there to produce multiples of the same row in the output, or just an error.
The attribute category in the last line of your query is not attributed to any of the tables (but I suspect it comes from the categories table).
Further, your code uses a GROUP BY clause with no aggregation function. This will produce non-deterministic results and is a bug. Assuming that you are not exploiting a side-effect of that, the query can be re-written as:
SELECT
category, b.fruit_name, u.name, r.count_vote, r.text_c
FROM Fruits b
JOIN Reviews r
ON r.fruit_id = b.fruit_id
JOIN Customers u ON u.customer_id = r.customer_id
ORDER BY r.fruit_id, count_vote DESC, r_id;
Since there are no predicates other than joins in your query, there is no scope for further optimization beyond ensuring there are indexes on the join predicates.
As all too frequently, the biggest benefit may come from simply asking the question of why you need to retrieve every single row in the tables in a single query.
Firstly, I'm a beginner to MySQL and I'm still learning. I'm trying to join 2 tables to display a count. Primarily, I use 2 codes. One code to display names -
SELECT tag_logs.timestamp, People.Name FROM `tag_logs` INNER JOIN People WHERE tag_logs.tag_no = People.nametag
Another code to display count of names -
SELECT tag_logs.tag_no, COUNT(tag_logs.tag_no) FROM tag_logs GROUP BY tag_no HAVING COUNT(tag_no) >= 1
I want to display Name and a count number, instead of a tag number and count. I attempted to join both tables by using the following code, however, I've had little luck -
SELECT People.Name FROM `tag_logs` INNER JOIN People WHERE tag_logs.tag_no = People.nametag AND COUNT(tag_logs.tag_no) FROM tag_logs GROUP BY tag_no HAVING COUNT(tag_no) >= 1
I'm given an error when I try to call 'FROM tag_logs' a second time. Is there a way to work around this?
I aim to make this my final result, except I should be able to see names instead of numbers.
Two tables are joined using ON clause. You should learn joins.
SELECT People.Name ,COUNT(tag_logs.tag_no)
FROM `tag_logs`
INNER JOIN People ON tag_logs.tag_no = People.nametag
GROUP BY tag_logs.tag_no
HAVING COUNT(tag_no) >= 1
It should be
SELECT People.Name FROM `tag_logs`
INNER JOIN People on tag_logs.tag_no = People.nametag
GROUP BY tag_no HAVING COUNT(tag_no) >= 1
EDIT
SELECT People.Name, COUNT(tag_no) FROM `tag_logs`
INNER JOIN People on tag_logs.tag_no = People.nametag
GROUP BY tag_no HAVING COUNT(tag_no) >= 1
I believe the query that you want looks like this:
SELECT p.Name, COUNT(*)
FROM tag_logs tl INNER JOIN
People p
ON tl.tag_no = p.nametag
GROUP BY p.Name;
Notes:
COUNT(*) is shorter than COUNT(tl.tag_no) and they do the same thing.
GROUP BY clause now matches the SELECT. If you could have people with the same names, then add p.nametag to the GROUP BY. A version use only GROUP BY tl.tag_no is invalid SQL and should fail in most databases, because of the non-matching p.Name in the SELECT.
The HAVING clause (HAVING COUNT(tag_no) >= 1) is unnecessary, because the INNER JOIN requires at least one match and tag_no is never NULL (because it is used for the JOIN).
I introduced table aliases, so the query is easier to write and to read.
I have 4 tables in an existing mysql database of a directory type site.
Table mt_links contains basic info for each listing
Table mt_cl contains which listing above is in what category (I only want cat_id=1)
Table mt_cfvalues contains more details for each listing It Can have repeated values
Table mt_images contains image names for each listing.
I want all records from mt_links where the mt_cl cat_id=1, and for each of those records, I need all records in mt_cfvalues and cf_images matching the link_id.
I set up a select with Group_Concat and left joins, but ended up with repeating values in my results. I added Distinct, which cured the repeating values, but mt_cfvalues can have records with the same value, so now I'm missing a value I should have.
SELECT a.link_id,
a.link_name,
a.link_desc,
GROUP_CONCAT(DISTINCT b.value ORDER BY b.cf_ID) AS details,
GROUP_CONCAT(DISTINCT c.filename ORDER BY c.ordering) AS images
FROM mt_links a
LEFT JOIN mt_cfvalues b ON a.link_id = b.link_ID
LEFT JOIN mt_images c ON b.link_id = c.link_ID
LEFT JOIN mt_cl d ON a.link_id = d.link_ID WHERE d.cat_ID = '1'
GROUP BY a.link_id
I put together a SQLFiddle here: http://www.sqlfiddle.com/#!2/f39e9/1
Is there an easier way? How do I fix the repeating / no repeating issue?
Here is one way of accomplishing what you seek. Because the two subqueries return independent results, you can't combine the GROUP BY, which is why you were getting duplicates.
SELECT a.link_id,
a.link_name,
a.link_desc,
cvf.details,
imgs.images
FROM mt_links a
LEFT JOIN (
SELECT link_ID, GROUP_CONCAT(value ORDER BY cf_ID) AS details
FROM mt_cfvalues
GROUP BY link_ID
) cvf ON cvf.link_ID = a.link_id
LEFT JOIN (
SELECT link_ID, GROUP_CONCAT(filename ORDER BY ordering) AS images
FROM mt_images
GROUP BY link_ID
) imgs ON imgs.link_ID = a.link_id
INNER JOIN mt_cl d ON a.link_id = d.link_ID
WHERE d.cat_ID = '1'
I'm writing a query whereby I'm trying to count the total number of records in report and assignment table, whiles at the same time retrieving information from the main table group. Group has a primary key id which is saved in the other tables as gid. This is the query:
SELECT `group`.`id` AS `gid`
, `group`.`name` AS `g_name`
, COUNT(`report`.`id`) AS `reports`
FROM `group`
LEFT OUTER JOIN `report` ON `report`.`gid` = `group`.`id`
LEFT OUTER JOIN `assignment` ON `assignment`.`gid` = `group`.`id`
WHERE `group`.`active` = 0
ORDER BY
`group`.`name`;
My problem is whenever I execute this only one record is returned even if theirs multiple groups.
Thanks in advance.
Well, your query is far from correct :) First of all, you should not have aggregated functions (in this case count) without a group by clause. Now, even if you have that clause the query will summarize information and you want both: the detail and a summary in the same query. I'd recommend 2 separate queries to retrieve this information, but if you want information mixed in only one query (the detail and also the "total number of records in report and assignment table") try the following query:
SELECT
`group`.id AS gid,
`group`.name AS g_name,
(SELECT COUNT(*) from report) as ReportTotalCount,
(SELECT COUNT(*) from assignment) as AssignmentTotalCount,
FROM `group`
WHERE `group`.`active` = 0
LEFT OUTER JOIN report ON report.gid = `group`.id
LEFT OUTER JOIN assignment ON assignment.gid = `group`.id
ORDER BY `group`.name;
I whish I could understand exactly what you're looking for but this might give you an idea on how to get the result you expect.
Can't see anything obvious in your query that would limit it to returning one record.
You are going to have to break it up to see where the problem is against your existing data.
So how many groups where acitive = 0, ahow many with a corresponding assignment record, etc.
maybe it will help:
SELECT
groupid,
groupname,
reports,
assignments,
FROM
(SELECT group.id, group.name, COUNT(*) AS reports from group
INNER JOIN report ON (report.gid = group.id)
WHERE group.active = 0
GROUP BY group.id ) AS ReportForGroup
CROSS JOIN
(SELECT group.id AS groupid, group.name AS groupname, COUNT(*) AS assignments from group
INNER JOIN assignmentON (assignment.gid = group.id)
WHERE group.active = 0
GROUP BY group.id ) AS AssignmentForGroup
ON (ReportForGroup.groupid = AssignmentForGroup.groupid)
ORDER BY groupname;
I'm can't check it so if LEFT JOIN returns to COUNT(*) 0 or 1. if it returns 0 just change the INNERs to LEFTs and use INNER JOIN between the two queries