I have the following tables
mixes
mid | date | info
1 | 2009-07-01 | no info yet
music-review
mid | song | buy
1 | Example - Example | http://example.com
2 | Exam - Exam | http://example.com
tracklist
tid | mid | mrid
1 | 1 | 1
2 | 1 | 2
is it possible to have an SQL query where you can link these all into one?
so my results would turn out like:
date | info | tracklist
2009-07-01 | no info yet | Example - Example http://example.com, Exam - Exam http://example.com
or however this result would be returned... or would this need to be a two sql querys where i get the MID from the mixes and then do a query to get the tracklist from that?
For MySQL:
SELECT mixes.date, mixes.info,
GROUP_CONCAT(DISTINCT music-review.song + ' ' + music-review.buy
ORDER BY music-review.mid ASC SEPARATOR ', ')
FROM mixes
JOIN tracklist ON tracklist.mid = mixes.mid
JOIN music-review ON music-review.mrid = tracklist.mrid
GROUP BY mixes.date, mixes.info
this works as adapted from mherren:
SELECT mixes.`date`, mixes.info,
CONCAT(GROUP_CONCAT(DISTINCT `music-review`.song , ' ' , `music-review`.`mid`
ORDER BY `tracklist`.`tid` ASC SEPARATOR ', ')) as `tracklist`
FROM mixes
JOIN tracklist ON tracklist.`mid` = mixes.`mid`
JOIN `music-review` ON tracklist.`mrid` = `music-review`.`mid`
WHERE `mixes`.`date`='2009-07-01'
GROUP BY mixes.`date`, mixes.info;
it fixes a blurb issue i was getting but, one thing is that group_concat has a max limit set at 1024 this can be altered tho by
SET GLOBAL group_concat_max_len=4096
I left so many comments, I thought it would be more helpful to suggest a revision to your architecture as an answer. However, I do think mherren has already competently addressed your actual concern, so while votes are appreciated, I don't think this should be considered as the the right "answer".
I think you need to reconsider how you have arranged the data. Specifically, you have a table for "music-review" that seems out of place while at the same time you refer to "mixes" and "tracklists" which seems a bit redundant. I imagine you want a one-to-many relationship where "mixes" refers to the information about the mix, like when it was created, the user who created it, etc. While "tracklist" is the list of songs within the "mix". What if you tried this:
#song-info
song_id | artist | title | online-store
1 | The Airheads | Asthma Attack! | example.com/?id=123
2 | The Boners | Bite the Boner | example.com/?id=456
3 | Cats in Heat | Catching a Cold | example.com/?id=789
4 | Dirty Djangos | Dig these Digits | example.com/?id=147
#mixes
mix_id | date | info
1 | 2009-07-01 | no info yet
2 | 2009-07-02 | no info yet
#mix_tracklist
mix_id | song_id
1 | 1
1 | 2
2 | 2
2 | 3
Now you can have a list of available mixes, and if a user selects a mix, another query for the actual songs.
Trying to put all of the song data into one column should only be done if the results require that info right away or if there is a condition within the query itself that is conditional to the results of that sub-query. If you simply want to output a list of mixes with the track list for each one, you are better of doing the query for each mix based on the mix index. So in the case of php outputting HTML, you would go with:
$mixes = mysql_query("SELECT * FROM mixes WHERE date > '$last_week'");
while($mix = mysql_fetch_assoc($mixes)) {
$mix_id = $mix['mix_id'];
$mix_date = date('m/d/Y', strtotime($mix['mix_id']));
$mix_info = $mix['mix_id'];
echo <<<EOT
<h2 class="mix_number">$mix_number</h2>
<p class="mix_date">$mix_date</p>
<p class="mix_info">$mix_info</p>
<h3>Track Listing:</h3>
<ul class="tracklist">
EOT;
$tracks = mysql_query("SELECT song.artist artist,
song.title title,
song.online-store url
song.song_id
FROM song-info song
JOIN mix_tracklist tracks ON (tracks.song_id = song.song_id)
WHERE tracks.mix_id = '$mix_id'
ORDER_BY song_id);
while ($track = mysql_fetch_assoc($tracks)) {
$artist = $track['artist'];
$song_name = $track['title'];
$song_url = $track['url'];
echo <<<EOT
<li>$artist – $song_name</li>
EOT;
}
echo "</ul>";
}
Related
I'm trying to create a query in SQL Server to determine how many times a person's name shows up in a list, but also that list will be unknown, so I would have to get the actual name from the previous select index... It's hard to explain so I'll show the query first and hopefully someone can help.
SELECT
SpeakerName, Spoken,
(SELECT COUNT(SpeakerName)
FROM tbl_SpeakerCard_Log
WHERE SpeakerName = 'SpeakerName[i]' AND SpeakDate = '3-9-16') as TimesSpoken
FROM
tbl_SpeakerCard_Log
WHERE
AID = ####
ORDER BY
GeneralComment ASC
So basically, in SpeakerName[i], I'd like to somehow get the SpeakerName from the outer Select. The output should come out something like this
+-------------+--------+-------------+
| SpeakerName | Spoken | TimesSpoken |
+-------------+--------+-------------+
| Holly | 0 | 4 |
| Robert | 1 | 5 |
| Mike | 1 | 2 |
+-------------+--------+-------------+
Try this:
select x.SpeakerName, x.Spoken, COUNT(*) as TimesSpoken
from tbl_SpeakerCard_Log x
WHERE AID = ####
and x.SpeakDate = '3-9-16'
group by x.SpeakerName, x.Spoken
Don't have SSMS installed on this computer so can't test it.
I am really new to SQL, and want to compare two values from two users: For example, the value for the first user at field_id=3, and the value for the second user at field_id=6. The table looks as follows:
+----------+---------+-------+
| field_id | user_id | value |
+----------+---------+-------+
| 1 | 1 | Name1 |
| 2 | 1 | Man |
| 3 | 1 | Woman |
| 1 | 2 | Name2 |
| 2 | 2 | Woman |
| 3 | 2 | Man |
+----------+---------+-------+
This check, I'm looking for, needs to become part of the following sql statement:
$sql = "SELECT MIN(us.ID) FROM ".$wpdb->base_prefix."users us"
. " JOIN ".$wpdb->base_prefix."bp_xprofile_data bp ON us.ID = bp.user_id"
. " JOIN ". $wpdb->base_prefix . "usermeta um ON um.user_id = us.ID"
. " WHERE um.meta_key = 'last_activity' AND us.ID > $current_id"
. " AND ?????????? What to insert here to compare?????"
The check, whether the value for field_id=2 and user_id=1 equals the value of field_id=3 and user_id=2, needs to replace above statement's ?????????? What to insert here to compare?????.
This query is called from php.
The plain comparison could be done like
SELECT
'match' AS result
FROM us_user U1
JOIN us_user U2
ON U1.value = U2.value
AND U1.field_id = 2
AND U1.user_id = 1
AND U2.field_id = 3
AND U2.user_id = 2
;
The exact 'return value' (I picked match, could be 1) is free for you to choose (and does not really need a column alias - as long as your database is easy about it).
See this in action: SQL Fiddle
This could then be made a subquery to be included into your original statement along
... AND EXISTS (suggested-query-goes-here)
You will most likely need to synch at least one of the tables in the suggested query to one of the tables in your existing statement. But which exactly, I'm not able to tell from the information provided so far.
Please comment, if and as this requires adjustment / further detail. In particular feel free to extend the Fiddle with structure and sample data for the other tables involved in order to set the full picture straight.
For an assignment I have to write several SQL queries for a database stored in a PostgreSQL server running PostgreSQL 9.3.0. However, I find myself blocked with last query. The database models a reservation system for an opera house. The query is about associating the a spectator the other spectators that assist to the same events every time.
The model looks like this:
Reservations table
id_res | create_date | tickets_presented | id_show | id_spectator | price | category
-------+---------------------+---------------------+---------+--------------+-------+----------
1 | 2015-08-05 17:45:03 | | 1 | 1 | 195 | 1
2 | 2014-03-15 14:51:08 | 2014-11-30 14:17:00 | 11 | 1 | 150 | 2
Spectators table
id_spectator | last_name | first_name | email | create_time | age
---------------+------------+------------+----------------------------------------+---------------------+-----
1 | gonzalez | colin | colin.gonzalez#gmail.com | 2014-03-15 14:21:30 | 22
2 | bequet | camille | bequet.camille#gmail.com | 2014-12-10 15:22:31 | 22
Shows table
id_show | name | kind | presentation_date | start_time | end_time | id_season | capacity_cat1 | capacity_cat2 | capacity_cat3 | price_cat1 | price_cat2 | price_cat3
---------+------------------------+--------+-------------------+------------+----------+-----------+---------------+---------------+---------------+------------+------------+------------
1 | madama butterfly | opera | 2015-09-05 | 19:30:00 | 21:30:00 | 2 | 315 | 630 | 945 | 195 | 150 | 100
2 | don giovanni | opera | 2015-09-12 | 19:30:00 | 21:45:00 | 2 | 315 | 630 | 945 | 195 | 150 | 100
So far I've started by writing a query to get the id of the spectator and the date of the show he's attending to, the query looks like this.
SELECT Reservations.id_spectator, Shows.presentation_date
FROM Reservations
LEFT JOIN Shows ON Reservations.id_show = Shows.id_show;
Could someone help me understand better the problem and hint me towards finding a solution. Thanks in advance.
So the result I'm expecting should be something like this
id_spectator | other_id_spectators
-------------+--------------------
1| 2,3
Meaning that every time spectator with id 1 went to a show, spectators 2 and 3 did too.
Note based on comments: Wanted to make clear that this answer may be of limited use as it was answered in the context of SQL-Server (tag was present at the time)
There is probably a better way to do it, but you could do it with the 'stuff 'function. The only drawback here is that, since your ids are ints, placing a comma between values will involve a work around (would need to be a string). Below is the method I can think of using a work around.
SELECT [id_spectator], [id_show]
, STUFF((SELECT ',' + CAST(A.[id_spectator] as NVARCHAR(10))
FROM reservations A
Where A.[id_show]=B.[id_show] AND a.[id_spectator] != b.[id_spectator] FOR XML PATH('')),1,1,'') As [other_id_spectators]
From reservations B
Group By [id_spectator], [id_show]
This will show you all other spectators that attended the same shows.
Meaning that every time spectator with id 1 went to a show, spectators 2 and 3 did too.
In other words, you want a list of ...
all spectators that have seen all the shows that a given spectator has seen (and possibly more than the given one)
This is a special case of relational division. We have assembled an arsenal of basic techniques here:
How to filter SQL results in a has-many-through relation
It is special because the list of shows each spectator has to have attended is dynamically determined by the given prime spectator.
Assuming that (d_spectator, id_show) is unique in reservations, which has not been clarified.
A UNIQUE constraint on those two columns (in that order) also provides the most important index.
For best performance in query 2 and 3 below also create an index with leading id_show.
1. Brute force
The primitive approach would be to form a sorted array of shows the given user has seen and compare the same array of others:
SELECT 1 AS id_spectator, array_agg(sub.id_spectator) AS id_other_spectators
FROM (
SELECT id_spectator
FROM reservations r
WHERE id_spectator <> 1
GROUP BY 1
HAVING array_agg(id_show ORDER BY id_show)
#> (SELECT array_agg(id_show ORDER BY id_show)
FROM reservations
WHERE id_spectator = 1)
) sub;
But this is potentially very expensive for big tables. The whole table hast to be processes, and in a rather expensive way, too.
2. Smarter
Use a CTE to determine relevant shows, then only consider those
WITH shows AS ( -- all shows of id 1; 1 row per show
SELECT id_spectator, id_show
FROM reservations
WHERE id_spectator = 1 -- your prime spectator here
)
SELECT sub.id_spectator, array_agg(sub.other) AS id_other_spectators
FROM (
SELECT s.id_spectator, r.id_spectator AS other
FROM shows s
JOIN reservations r USING (id_show)
WHERE r.id_spectator <> s.id_spectator
GROUP BY 1,2
HAVING count(*) = (SELECT count(*) FROM shows)
) sub
GROUP BY 1;
#> is the "contains2 operator for arrays - so we get all spectators that have at least seen the same shows.
Faster than 1. because only relevant shows are considered.
3. Real smart
To also exclude spectators that are not going to qualify early from the query, use a recursive CTE:
WITH RECURSIVE shows AS ( -- produces exactly 1 row
SELECT id_spectator, array_agg(id_show) AS shows, count(*) AS ct
FROM reservations
WHERE id_spectator = 1 -- your prime spectator here
GROUP BY 1
)
, cte AS (
SELECT r.id_spectator, 1 AS idx
FROM shows s
JOIN reservations r ON r.id_show = s.shows[1]
WHERE r.id_spectator <> s.id_spectator
UNION ALL
SELECT r.id_spectator, idx + 1
FROM cte c
JOIN reservations r USING (id_spectator)
JOIN shows s ON s.shows[c.idx + 1] = r.id_show
)
SELECT s.id_spectator, array_agg(c.id_spectator) AS id_other_spectators
FROM shows s
JOIN cte c ON c.idx = s.ct -- has an entry for every show
GROUP BY 1;
Note that the first CTE is non-recursive. Only the second part is recursive (iterative really).
This should be fastest for small selections from big tables. Row that don't qualify are excluded early. the two indices I mentioned are essential.
SQL Fiddle demonstrating all three.
It sounds like you have one half of the total question--determining which id_shows a particular id_spectator attended.
What you want to ask yourself is how you can determine which id_spectators attended an id_show, given an id_show. Once you have that, combine the two answers to get the full result.
So the final answer I got, looks like this :
SELECT id_spectator, id_show,(
SELECT string_agg(to_char(A.id_spectator, '999'), ',')
FROM Reservations A
WHERE A.id_show=B.id_show
) AS other_id_spectators
FROM Reservations B
GROUP By id_spectator, id_show
ORDER BY id_spectator ASC;
Which prints something like this:
id_spectator | id_show | other_id_spectators
-------------+---------+---------------------
1 | 1 | 1, 2, 9
1 | 14 | 1, 2
Which suits my needs, however if you have any improvements to offer, please share :) Thanks again everybody!
I have a question concerning MS Access queries involving these tables:
tblMIDProcessMain ={ Process_ID,Process_Title,...}
tblMIDProcessVersion = { ProcessVersion_ID, ProcessVersion_FK_Process, ProcessVersion_VersionNo, ProcessVersion_FK_Status, ...}
tblMIDProcessVersionStatus = { ProcessVersionStatus_ID,ProcessVersionStatus_Value }
The tables store different versions of a process description. The "ProcessVersion_VersionNo" field contains an integer providing the version number. Now I would like to get for each process the highest version number thus the current version. If I do the following it kind of works:
SELECT tblMIDProcessMain.Process_Titel
, Max(tblMIDProcessVersion.ProcessVersion_VersionNo) AS CurrentVersion
FROM tblMIDProcessMain
INNER JOIN tblMIDProcessVersion
ON tblMIDProcessMain.Process_ID = tblMIDProcessVersion.ProcessVersion_FK_Process
GROUP BY tblMIDProcessMain.Process_Titel;
The query returns a recordset with each existing process_title and the respective max number of the version field. But as soon as I add other fields like "ProcessVersion_FK_Status" in the Select statement the query stops working.
Any help would be appreciated. Thanks in advance.
Jon
Edit:
To clarify things a little I added a simplified example
Parent-Table:
Process_ID | Process_Title
----------------------------------
1 | "MyProcess"
2 | "YourProcess"
Child-Table:
Version_ID | Version_FK_ProcessID | Version_No | Version_Status
---------------------------------------------------------------------------
1 | 1 | 1 | "New"
2 | 2 | 1 | "Discarded"
3 | 2 | 2 | "Reviewed"
4 | 2 | 3 | "Released"
Intended Result:
Title | Max_Version_No | Status
--------------------------------------------------------
MyProcess | 1 | "New"
YourProcess | 3 | "Released"
Given the example tables you updated your post with, this should work:
select process_title as Title
, max_version.max_version_no
, c.version_status as status
from (parenttable p
inner join (select max(version_id) as max_version_no, version_fk_process_id from childtable group by version_fk_process_id) max_version
on p.process_id = max_version.version_fk_process_id)
inner join childtable c
on max_version.max_version_no = c.version_id and max_version.version_fk_process_id = c.version_fk_process_id
I assume you are adding the new field to the 'Group By" clause? If not, then you either must include in the 'Group By', or you must use one of the operators like "Max" or "First" etc.
Good morning all, apologies for the title... i had trouble simplifying the problem down to a line. My database platform is Teradata.
I am working w/ a table like the following (let's call it "t1")
+------------+----------------------------------------+
| Service_Id | Product |
+------------+----------------------------------------+
| 1 | Traffic |
| 1 | Weather |
| 1 | Travel |
| 1 | Audio |
| 1 | Audio Add-on |
| 2 | Traffic |
| 2 | Weather |
| 2 | Travel |
+------------+----------------------------------------+
I am trying to select service_id's that are related to the following products AND ONLY the following products: Traffic, Weather, Travel
"Service_Id = 1" does not apply here because while it has the required products, it also has an "audio" product related to it... so we have to leave it out. I was able to successfully do this through a series of temp (volatile) tables but it's feeling really hacky and I feel there's got to be a better way. Thanks for your assistance.
I'm doing stuff like that (find a subset/superset/exact match for a set of rows) in my training classes using pizzas :-)
There are several ways to get your result, but for an exact match the easiest way is a SUM using following logic:
SELECT service_id
FROM t1
GROUP BY 1
HAVING
SUM(CASE WHEN Product IN ('Traffic', 'Weather', 'Travel') THEN 1 ELSE -1 END = 3
Assuming that Product is unique for every service_ID.
SELECT service_ID
FROM tableName a
WHERE Product IN ('Traffic', 'Weather', 'Travel') AND
EXISTS
(
SELECT 1
FROM tableName b
WHERE a.Service_ID = b.Service_ID
GROUP BY b.Service_ID
HAVING COUNT(*) = 3 -- <<== total number of products
)
GROUP BY service_ID
HAVING COUNT(*) = 3 -- <<== total number of products
SQLFiddle Demo (demo is running under MySQL database, not sure if it will work on teradata)