I searched, but seems I haven't found the right keyword for describing what I am trying to achieve, so please be lenient if this is a known problem, just point me to the right keywords.
I have following tables/entries:
select * from personnes where id=66;
id | aclid | referendid | login | validated | passwd
66 | | | toto#tiiti.com | f | $2y$10$w3DRh/g2Tebu/mkMcQz32OUB.dDjFiBP99vWlMrrPWpR45JZDdw4W
and
select * from pattributs where (name='nom' OR name='prenom') AND persid=66;
id | name | value | persid
----+--------+-------+--------
90 | prenom | Jean | 66
91 | nom | Meyer | 66
Now I use that form for not cluttering the main table, since depending on the case, I record the name, or not....
but having a view as a table of the completed table would be nice, so I tried:
select (personnes."id","login",
(select "value" from pattributs where "name"='nom' AND "persid"=66),
(select "value" from pattributs where "name"='prenom' AND "persid"=66)
) from personnes where personnes.id=66;
which seems to do the job:
row
--------------------------------
(66,toto#tiiti.com,Meyer,Jean)
but the column tags disappeared, and being able to fetch them from the invoking php script is immensely useful, but when I add:
select (personnes."id","login",
(select "value" from pattributs where "name"='nom' AND "persid"=66),
(select "value" from pattributs where "name"='prenom' AND "persid"=66) as 'prenom')
from personnes where personnes.id=66;
I get a syntax error at the as directive... So probably I haven't understood how to do this properly, the braces indicate that this isn't anymore in tabular form), so how can I achieve the following result:
id | login | nom | prenom
66 |toto#tiiti.com | Meyer | Jean
The idea being to store a suitable view for each use case, bundling only the relevant columns.
Thanks in advance
To answer your question: You are loosing the column names because you are creating a simple data set, a row. This is done by your braces. Without them you should get your expected result.
But your solution is not very well: You should avoid to calculate your single columns in every single subquery. This could be done easily in one SELECT:
select
pe.id,
pe.login,
MIN(pa.value) FILTER (WHERE pa.name = 'nom') as nom,
MIN(pa.value) FILTER (WHERE pa.name = 'prenom') as prenom
from
personnes pe
join pattributs pa ON pe.id = pa.persid AND pe.id = 66
where pa.name = 'nom' or pa.name = 'prenom'
group by pe.id, pe.login
First you'll need a JOIN to get the right datasets of both tables together. You should join on the id.
Then you have the problem that you have two rows for the name (which seems not very well designed, why not two columns?). These two values can be grouped by the id. Now you could aggregate them.
What I am doing is to "aggregate" them (it doesn't matter what function I am using because it should be only one value). The FILTER clause filters out the right value.
Related
I have the following SQL query:
SELECT TOP 3 accounts.username
,COUNT(accounts.username) AS count
FROM relationships
JOIN accounts ON relationships.account = accounts.id
WHERE relationships.following = 4
AND relationships.account IN (
SELECT relationships.following
FROM relationships
WHERE relationships.account = 8
);
I want to return the total count of accounts.username and the first 3 accounts.username (in no particular order). Unfortunately accounts.username and COUNT(accounts.username) cannot coexist. The query works fine removing one of the them. I don't want to send the request twice with different select bodies. The count column could span to 1000+ so I would prefer to calculate it in SQL rather in code.
The current query returns the error Column 'accounts.username' is invalid in the select list because it is not contained in either an aggregate function or the GROUP BY clause. which has not led me anywhere and this is different to other questions as I do not want to use the 'group by' clause. Is there a way to do this with FOR JSON AUTO?
The desired output could be:
+-------+----------+
| count | username |
+-------+----------+
| 1551 | simon1 |
| 1551 | simon2 |
| 1551 | simon3 |
+-------+----------+
or
+----------------------------------------------------------------+
| JSON_F52E2B61-18A1-11d1-B105-00805F49916B |
+----------------------------------------------------------------+
| [{"count": 1551, "usernames": ["simon1", "simon2", "simon3"]}] |
+----------------------------------------------------------------+
If you want to display the total count of rows that satisfy the filter conditions (and where username is not null) in an additional column in your resultset, then you could use window functions:
SELECT TOP 3
a.username,
COUNT(a.username) OVER() AS cnt
FROM relationships r
JOIN accounts a ON r.account = a.id
WHERE
r.following = 4
AND EXISTS (
SELECT 1 FROM relationships t1 WHERE r1.account = 8 AND r1.following = r.account
)
;
Side notes:
if username is not nullable, use COUNT(*) rather than COUNT(a.username): this is more efficient since it does not require the database to check every value for nullity
table aliases make the query easier to write, read and maintain
I usually prefer EXISTS over IN (but here this is mostly a matter of taste, as both techniques should work fine for your use case)
I am working on a query that will fetch multipart messages from 2 tables. However, it only works IF there are multiple parts. If there is only a one part message then the the join condition won't be true anymore. How could I make it to work for both single and multipart messages?
Right now it fails if there is an entry in outbox and nothing in outbox_multipart.
My first table is "outbox" that looks like this.
TextDecoded | ID | CreatorID
Helllo, m.. | 123 | Martin
Yes, I wi.. | 124 | Martin
My second table is "outbox_multipart" that looks very similar.
TextDecoded | ID | SequencePosition
my name i.. | 123 | 2
s Martin. | 123 | 3
ll do tha.. | 124 | 2
t tomorrow. | 124 | 3
My query so far
SELECT
CONCAT(ob.TextDecoded,
GROUP_CONCAT(obm.TextDecoded
ORDER BY obm.SequencePosition ASC
SEPARATOR ''
)
) AS TextDecoded,
ob.ID,
ob.creatorID
FROM outbox AS ob
JOIN outbox_multipart AS obm ON obm.ID = ob.ID
GROUP BY
ob.ID,
ob.creatorID
Use a left join instead of an (implicit) inner join. Then, also use COALESCE on the TextDecoded alias to make sure that empty string (and not NULL) appears in the expected output.
SELECT
CONCAT(ob.TextDecoded,
COALESCE(GROUP_CONCAT(obm.TextDecoded
ORDER BY obm.SequencePosition
SEPARATOR ''), '')) AS TextDecoded,
ob.ID,
ob.creatorID
FROM outbox AS ob
LEFT JOIN outbox_multipart AS obm
ON obm.ID = ob.ID
GROUP BY
ob.ID,
ob.creatorID,
ob.TextDecoded;
Note: Strictly speaking, outbox.TextDecoded should also appear in the GROUP BY clause, since it is not an aggregate. I have made this change in the query.
I'm working on a filter where the user can choose different conditions for the end output. Right now I'm doing the construction of the SQL query, but whenever more conditions are selected, it doesn't work.
Example of the advalues table.
+----+-----------+---------------+------------+
| id | listingId | value | identifier |
+----+-----------+---------------+------------+
| 1 | 1a | Alaskan Husky | race |
+----+-----------+---------------+------------+
| 2 | 1a | Højt | activity |
+----+-----------+---------------+------------+
| 3 | 1c | Akita | race |
+----+-----------+---------------+------------+
| 4 | 1c | Mellem | activity |
+----+-----------+---------------+------------+
As you can see, there's a different row for each advalue.
The outcome I expect
Let's say the user has checked/ticked the checkbox for the race where it says "Alaskan Husky", then it should return the listingId for the match (once). If the user has selected both "Alaskan Husky" and activity level to "Low" then it should return nothing, if the activity level is either "Mellem" or "Højt" (medium, high), then it should return the listingId for where the race is "Alaskan Husky" only, not "Akita". I hope you understand what I'm trying to accomplish.
I tried something like this, which returns nothing.
SELECT * FROM advalues WHERE (identifier="activity" AND value IN("Mellem","Højt")) AND (identifier="race" AND value IN("Alaskan Husky"))
By the way, I want to select distinct listingId as well, so it only returns unique listingId's.
I will continue to search around for solutions, which I've been doing for the past few hours, but wanted to post here too, since I haven't been able to find anything that helped me yet. Thanks!
You can split the restictions on identifier in two tables for each type. Then you join on listingid to obtain the listingId wich have the two type of identifier.
SELECT ad.listingId
FROM advalues ad
JOIN advalues ad2
ON ad.listingId = ad2.listingId
WHERE ( ad.identifier = 'activity' AND ad.value IN( 'Mellem', 'Højt' ) )
AND ( ad2.identifier = 'race' AND ad2.value IN( 'Alaskan Husky' ) )
The question isn't exactly clear, but I think you want this:
WHERE (identifier="activity" AND value IN("Mellem","Højt")) OR (identifier="race" AND value IN("Alaskan Husky"))
If I got you right you are trying to fetch data with different "filters".
Your Query
SELECT listingId FROM advalues
WHERE identifier="activity"
AND value IN("Mellem","Højt")
AND identifier="race"
AND value IN("Alaskan Husky")
Will always return 0 results as you are asking for identifier = "activity" AND identifier = "race"
I think you wanted to do something like this instead:
SELECT listingId FROM advalues
WHERE
(identifier="activity" AND value IN("Mellem","Højt"))
OR
(identifier="race" AND value IN("Alaskan Husky"))
I have a query I need to perform to show search results for a project. What needs to happen, I need to sort the results by the "horsesActiveDate" and this applies to all of them except for any ad with the adtypesID=7. Those results are sorted by date but they must always result after all other ads.
So I will have all my ads in the result set be ordered by the Active Date AND adtypesID != 7. After that, I need all adtypesID=7 to be sorted by Active Date and appended at the bottom of all the results.
I'm hoping to put this in one query instead of two and appending them together in PHP. The way the code is written, I have to find a way to get it all in one query.
So here is my original query which has worked great until I had to ad the adtypesID=7 which has different sorting requirements.
This is the query that exists now that doesn't take into account the adtypesID for sorting.
SELECT
horses.horsesID,
horsesDescription,
horsesActiveDate,
adtypesID,
states.statesName,
horses_images.himagesPath
FROM horses
LEFT JOIN states ON horses.statesID = states.statesID
LEFT JOIN horses_images ON horses_images.himagesDefault = 1 AND horses_images.horsesID = horses.horsesID AND horses_images.himagesPath != ''
WHERE
horses.horsesStud = 0
AND horses.horsesSold = 0
AND horses.horsesID IN
(
SELECT DISTINCT horses.horsesID
FROM horses
LEFT JOIN horses_featured ON horses_featured.horsesID = horses.horsesID
WHERE horses.horsesActive = 1
)
ORDER BY adtypesID, horses.horsesActiveDate DESC
My first thought was to do two queries where one looked for all the ads that did not contain adtypesID=7 and sort those as the query does, then run a second query to find only those ads with adtypesID=7 and sort those by date. Then take those two results and append them to each other. Since I need to get this all into one query, I can't use a php function to do that.
Is there a way to merge the two query results one after the other in mysql? Is there a better way to run this query that will accomplish this sorting?
The Ideal Results would be as below (I modified the column names so they would be shorter):
ID | Description | ActiveDate | adtypesID | statesName | himagesPath
___________________________________________________________________________
3 | Ad Text | 06-01-2010 | 3 | OK | image.jpg
2 | Ad Text | 05-31-2010 | 2 | LA | image1.jpg
9 | Ad Text | 03-01-2010 | 4 | OK | image3.jpg
6 | Ad Text | 06-01-2010 | 7 | OK | image5.jpg
6 | Ad Text | 05-01-2010 | 7 | OK | image5.jpg
6 | Ad Text | 04-01-2010 | 7 | OK | image5.jpg
Any help that can be provided will be greatly appreciated!
I am not sure about the exact syntax in MySQL, but something like
ORDER BY case when adtypesID = 7 then 2 else 1 end ASC, horses.horsesActiveDate DESC
would work in many other SQL dielects.
Note that most SQL dialects allow the order by to not only be a column, but an expression.
This should work:
ORDER BY (adtypesID = 7) ASC, horses.horsesActiveDate DESC
Use a Union to append two queries together, like this:
SELECT whatever FROM wherever ORDER BY something AND adtypesID!=7
UNION
SELECT another FROM somewhere ORDER BY whocares AND adtypesID=7
http://dev.mysql.com/doc/refman/5.0/en/union.html
I re-wrote your query as:
SELECT h.horsesID,
h.horsesDescription,
h.horsesActiveDate,
adtypesID,
s.statesName,
hi.himagesPath
FROM HORSES h
LEFT JOIN STATES s ON s.stateid = h.statesID
LEFT JOIN HORSES_IMAGES hi ON hi.horsesID = h.horsesID
AND hi.himagesDefault = 1
AND hi.himagesPath != ''
LEFT JOIN HORSES_FEATURED hf ON hf.horsesID = h.horsesID
WHERE h.horsesStud = 0
AND h.horsesSold = 0
AND h.horsesActive = 1
ORDER BY (adtypesID = 7) ASC, h.horsesActiveDate DESC
The IN subquery, using a LEFT JOIN and such, will mean that any horse record whose horsesActive value is 1 will be returned - regardless if they have an associated HORSES_FEATURED record. I leave it to you for checking your data to decide if it should really be an INNER JOIN. Likewise for the STATES table relationship...
I have two tables, one for routes and one for airports.
Routes contains just over 9000 rows and I have indexed every column.
Airports only 2000 rows and I have also indexed every column.
When I run this query it can take up to 35 seconds to return 300 rows:
SELECT routes.* , a1.name as origin_name, a2.name as destination_name FROM routes
LEFT JOIN airports a1 ON a1.IATA = routes.origin
LEFT JOIN airports a2 ON a2.IATA = routes.destination
WHERE routes_build.carrier = "Carrier Name"
Running it with "DESCRIBE" I get the followinf info, but I'm not 100% sure on what it's telling me.
id | Select Type | Table | Type | possible_keys | Key | Key_len | ref | rows | Extra
--------------------------------------------------------------------------------------------------------------------------------------
1 | SIMPLE | routes_build | ref | carrier,carrier_2 | carrier | 678 | const | 26 | Using where
--------------------------------------------------------------------------------------------------------------------------------------
1 | SIMPLE | a1 | ALL | NULL | NULL | NULL | NULL | 5389 |
--------------------------------------------------------------------------------------------------------------------------------------
1 | SIMPLE | a2 | ALL | NULL | NULL | NULL | NULL | 5389 |
--------------------------------------------------------------------------------------------------------------------------------------
The only alternative I can think of is to run two separate queries and join them up with PHP although, I can't believe something like this being something that could kill a mysql server. So as usual, I suspect I'm doing something stupid. SQL is my number 1 weakness.
Personally, I would start by removing the left joins and replacing them with inner joins as each route must have a start and end point.
It's telling you that it's not using an index for joining on the airports table. See how the "rows" column is so huge, 5000 odd? that's how many rows it's having to read to answer your query.
I don't know why, as you have claimed you have indexed every column. What is IATA? Is it Unique? I believe if mysql decides the index is inefficient it may ignore it.
EDIT: if IATA is a unique string, maybe try indexing half of it only? (You can select how many characters to index) That may give mysql an index it can use.
SELECT routes.*, a1.name as origin_name, a2.name as destination_name
FROM routes_build
LEFT JOIN
airports a1
ON a1.IATA = routes_build.origin
LEFT JOIN
airports a2
ON a2.IATA = routes_build.destination
WHERE routes_build.carrier = "Carrier Name"
From your EXPLAIN PLAN I can see that you don't have an index on airports.IATA.
You should create it for the query to work fast.
Name also suggests that it should be a UNIQUE index, since IATA codes are unique.
Update:
Please post your table definition. Issue this query to show it:
SHOW CREATE TABLE airports
Also I should note that your FULLTEXT index on IATA is useless unless you have set ft_max_word_len is MySQL configuration to 3 or less.
By default, it's 4.
IATA codes are 3 characters long, and MySQL doesn't search for such short words using FULLTEXT with default settings.
After you implement Martin Robins's excellent advice (i.e. remove every instance of the word LEFT from your query), try giving routes_build a compound index on carrier, origin, and destination.
It really depends on what information you're trying to get to. You probably don't need to join airports twice and you probably don't need to use left joins. Also, if you can search on a numeric field rather than a text field, that would speed things up as well.
So what are you trying to fetch?