MySQL: OUTER JOIN and COUNT() - php

I have table 'posters', table 'reviews' and table 'trailers'. Every table is connected with an movieID column, but each table can be empty for certain movieIDs:
++ posters_table +++ ++ reviews_table ++ ++ trailers_table ++
--itemID--+--filename- --itemID--+--review-- --itemID--+--trailer
---------------------- --------------------- ---------------------
----001---+--0012343-- ----004---+--blalba-- ----002---+--002345--
----001---+--0013331-- ----004---+--xlalxa-- ----005---+--005434--
----002---+--0020052-- ----005---+--zlalza-- ----001---+--005335--
I want to COUNT() the number of posters, reviews and trailers for the specified movieID and get 0 if no available.
So if I want to count movieID = 001 I get: ['posters'] = 2 / ['reviews'] = 0 and ['trailers'] = 1 (for example)
Can someone post the SQL query to do this?


select
(select count(*) from posters_table where itemId = ?) as posters,
(select count(*) from reviews_table where itemId = ?) as reviews,
(select count(*) from trailers_table where itemId = ?) as trailers;


I think if you JOIN the movie table to a result set that gives the count, you can then pick out whether or not the count is > 0 and give the appropriate value:
SELECT movieID, IF(posters.posters_count > 0, posters.posters_count,0) AS posters_total, IF(reviews.reviews_count > 0, reviews.reviews_count,0) AS reviews_total, IF(trailers.trailers_count > 0, trailers.trailers_count,0) AS trailers_total
FROM movies m
LEFT JOIN (SELECT itemID,COUNT(*) AS posters_count FROM posters_table WHERE itemID = '001' GROUP BY itemID) posters ON posters.itemID = movies.movieID
LEFT JOIN (SELECT itemID,COUNT(*) AS reviews_count FROM reviews_table WHERE itemID = '001' GROUP BY itemID) reviews ON reviews.itemID = movies.movieID
LEFT JOIN (SELECT itemID,COUNT(*) AS trailers_count FROM trailers_table WHERE itemID = '001' GROUP BY itemID) trailers ON trailers.itemID = movies.movieID
WHERE m.movieID = '001'
EDIT: I prefers ar's solution. Much simpler!


select
(select count(P.movieid) from posters P where P.movieid=1),
(select count(R.movieid) from reviews R where R.movieid=1),
(select count(T.movieid) from trailers T where T.movieid=1)
The tables are not "really" joined so you need three selects.

Related

Count number of rows for specific ID

In first table album has id and second table album_details has sub_id which relates from album table id
I need to display count for separate id value.
SELECT DISTINCT B.SUB_ID, A . * , B.CONTENT_VALUE AS detail,
(SELECT COUNT( ID )
FROM album_details WHERE A.ID = B.SUB_ID ) AS count
FROM album AS A, album_details AS B
WHERE A.WEBSITE_ID = '571710720'
AND A.ID = B.SUB_ID
GROUP BY B.SUB_ID
LIMIT 0 , 30
Now count column shows 40 for all rows but need to display 'count' 6 for 'id=4', 'count' 3 for 'id=2'

SELECT count(SUB_ID),SUB_ID from album_details group by SUB_ID

GROUP BY is your weapon of choice.
SELECT
a.ID,
a.CONTENT_VALUE,
COUNT(ad.ID)
FROM albums AS a
LEFT JOIN album_details AS ad ON a.ID = ad.SUB_ID
GROUP BY a.ID
Feel free to add your WHERE before the GROUP BY.

Lets say first table is A and second table is B then query will be like this
select a.ID, count(b.SUB_ID) AS total
FROM A LEFT JOIN B ON A.ID = B.SUB_ID
Group by B.SUB_ID.
It might help you. If not then ask please.

select count(sub_id) as count1 from album_details where sub_id in(select id from album) WHERE album.WEBSITE_ID = '571710720'
AND album.ID = album_details.SUB_ID

How to get count of records which have duplicate value in mysql

I have a table with player and status, this table not got corrupted and it has duplicate entries like this:
player_id status
----------------------
1 100
2 100
2 101
3 100
1 101
2 101
As you can see this record is duplicate: 2,101
How can I find such records using a mysql query?
I tried:
select * from player group by player_id, status having count(status) > 1 but it did not help.

You can SELECT duplicate records as like that:
SELECT COUNT(*) as total,player_id,`status`
FROM `player`
GROUP BY player_id,`status`
HAVING total > 1;

Do it in a outer query like
select * from (
select *, count(*) as rowcount
from player
group by player_id, status ) tab
where rowcount > 1

You can try this query.
$qrys = <<<QUERY
select s.id, t.*
from player s
join (
select player_id, status, count(*) as qty
from player
group by player_id, status
having count(*) > 1
) t on s.player_id = t.player_id and s.status = t.status
QUERY;
If you want to delete duplicate record then use this script
$delres= mysql_query($qrys);
$player_id = 0;
$status = 0;
while ($r= mysql_fetch_array($delres)){
if($player_id == $r['player_id'] && $status == $r['status'])
mysql_query("DELETE FROM player WHERE id=".$r['id']);
$player_id = $r['player_id'];
$status = $r['status'];
}

Try this :
select * from player p
inner join ( select player_id, count(*) as duplicate
from player group by player_id
having count(*) > 1) pp
on p.player_id = pp.player_id

Try This
SELECT *, COUNT(status) AS rows_count FROM player
GROUP BY player_id, status HAVING COUNT(status) > 0

You query is near to it just some changes in it to give you count column for every options Try this modified query.
select *, count(status) as count from player
group by player_id, status having count(status) > 0
It will give this type of response

you can do that by
SELECT distinct player .*
FROM player as tb1
join player as tb2
WHERE tb1.status = tb2.status
and tb1.player_id < tb2.player_id

You can do it simply with GROUP BY like this
SELECT `player_id`, `status`, COUNT(*) as cnt FROM `player`
GROUP BY CONCAT(`player_id`, '_', `status`) HAVING cnt > 1
result would be
player_id status cnt
2 101 2

Limiting a left join to returning one result?

I currently have this left join as part of a query:
LEFT JOIN movies t3 ON t1.movie_id = t3.movie_id AND t3.popularity = 0
The trouble is that if there are several movies with the same name and same popularity (don't ask, it just is that way :-) ) then duplicate results are returned.
All that to say, I would like to limit the result of the left join to one.
I tried this:
LEFT JOIN
(SELECT t3.movie_name FROM movies t3 WHERE t3.popularity = 0 LIMIT 1)
ON t1.movie_id = t3.movie_id AND t3.popularity = 0
The second query dies with the error:
Every derived table must have its own alias
I know what I'm asking is slightly vague since I'm not providing the full query, but is what I'm asking generally possible?

The error is clear -- you just need to create an alias for the subquery following its closing ) and use it in your ON clause since every table, derived or real, must have its own identifier. Then, you'll need to include movie_id in the subquery's select list to be able to join on it. Since the subquery already includes WHERE popularity = 0, you don't need to include it in the join's ON clause.
LEFT JOIN (
SELECT
movie_id,
movie_name
FROM movies
WHERE popularity = 0
ORDER BY movie_name
LIMIT 1
) the_alias ON t1.movie_id = the_alias.movie_id
If you are using one of these columns in the outer SELECT, reference it via the_alias.movie_name for example.
Update after understanding the requirement better:
To get one per group to join against, you can use an aggregate MAX() or MIN() on the movie_id and group it in the subquery. No subquery LIMIT is then necessary -- you'll receive the first movie_id per name withMIN() or the last with MAX().
LEFT JOIN (
SELECT
movie_name,
MIN(movie_id) AS movie_id
FROM movies
WHERE popularity = 0
GROUP BY movie_name
) the_alias ON t1.movie_id = the_alias.movie_id

LEFT JOIN movies as m ON m.id = (
SELECT id FROM movies mm WHERE mm.movie_id = t1.movie_id
ORDER BY mm.id DESC
LIMIT 1
)

you could try to add GROUP BY t3.movie_id to the first query

Try this:
LEFT JOIN
(
SELECT t3.movie_name, t3.popularity
FROM movies t3 WHERE t3.popularity = 0 LIMIT 1
) XX
ON t1.movie_id = XX.movie_id AND XX.popularity = 0

On MySQL 5.7+ use ANY_VALUE & GROUP_BY:
SELECT t1.id,t1.movie_name, ANY_VALUE(t3.popularity) popularity
FROM t1
LEFT JOIN t3 ON (t3.movie_id=t1.movie_id AND t3.popularity=0)
GROUP BY t1.id
more info
LEFT JOIN only first row
https://dev.mysql.com/doc/refman/5.7/en/group-by-handling.html

Easy solution to left join the 1 most/least recent row is using select over ON phrase
SELECT A.ID, A.Name, B.Content
FROM A
LEFT JOIN B
ON A.id = (SELECT MAX(id) FROM B WHERE id = A.id)
Where A.id is the auto-incremental primary key.

LEFT JOIN (
SELECT id,movie_name FROM movies GROUP BY id
) as m ON (
m.id = x.id
)

// Mysql
SELECT SUM(db.item_sales_nsv) as total FROM app_product_hqsales_otc as db
LEFT JOIN app_item_target_otc as it ON
db.id = (SELECT MAX(id) FROM app_item_target_otc as ot WHERE id = db.id)
and db.head_quarter = it.hqcode
AND db.aaina_item_code = it.aaina_item_code AND db.month = it.month
AND db.year = it.year
WHERE db.head_quarter = 'WIN001' AND db.month = '5' AND db.year = '2022' AND db.status = '1'

Slow query with IN operator

I am having a problem with one query. I am sure that the problem is IN operator but I don't know how and with what should I replace it?
Query:
SELECT `a`.`title`, `a`.`askprice`, `a`.`picture`, `a`.`description`, `a`.`userid`,
`a`.`id`
FROM (`mm_ads` AS a)
LEFT JOIN `mm_ads_fields_values` AS afv ON `a`.`id` = `afv`.`aid`
WHERE `a`.`status` = 1
AND `a`.`category` = '230'
AND `a`.`id` IN (2194,2200,2205,2215,2233,2238,2240,0,2243,2255,2257,2260,2263,2264,2266,2269,2272,2274,2276,2277,2279,2282,2284,2286,2288,2293,2297,2300,2303,2306,2310,2311,2318,2322,2324,2326,2330,2335,2340,2347,2351,2357,2364,2370,2375,2387,2391,2399,2404,2408,2413,2571,2574,2576,2578,2580,2582,2584,2586,2588,2590,2592,2597,2599,2601,2605,2606,2612,2615,2618,2621,2626,2628,2632,2637,2639,2641,2643,2646,2647,2653,2662,2664,2667,2670,2673,2677,2680,2687,2689,2691,2693,2696,2698,2701,2703,2705,2708,2710,2711,3666,3674,3693,3697,3704,3711,3718,3727,3732,3736,3761,3764,3771,3776,3779,3786,3802,3807,3813,3818,3844,3847,3853,3866,3870,3873,3879,3883,4283,4287,4292,4300,4305,4313,4332,4339,4348,4354,4361,4367,4371,4378,4391,4412,4424,4441,4445,4451,4458,4466,4473,4479,4494,4508,4515,4523,4530,4537,4541,4542,4575,4584,4602,4621,4629,4638,4647,4652,4659,4665,4670,4677,4684,4690,4693,4702,4712,4720,4726,4732,4740,4747,4755,4763,4772,4776,4779,4784,4788,4790,4793,4797,4802,4807,4811,4818,4824,4831,4839,4844,4848,4851,4855,4867,4873,4877,4887,4894,4897,4901,4908,4912,4916,4926,4932,4939,4944,4949,4956,4959,4968,4977,4981,5001,5008,5012,5015,5021,5027,5034,5038,5045,5048,5053,5058,5063,5066,5070,5071,5077,5080,5085,5089,5096,5104,5108,5113,5114,5120,5127,5131,5135,5141,5150,5155,5159,5170,5174,5179,5187,5196,5205,5209,5215,5236,5254,5273,5281,5290,5309,5319,5323,5327,5350,5357,5363,5364,5372,5378,5409,5425,5434,5442,5461,5468,5477,5489,5497,5501,5515,5522,5529,5536,5541,5548,5558,5569,5585,5591,5597,5611,5619,5626,5635,5644,5653,5661,5667,5680,5688,5695,5702,5713,5725,5730,5734,5766,5781,5830,5882,5896,5928,5936,5943,5952,5958,5973,5998,6007,6018,6026,6083,6097,6103,6109,6114,6119,6124,6130,6136,6144,6152,6158,6172,6181,6192,6202,6211,6218,6223,6226,6230,6234,6239,6246,6256,6259,6266,6269,6273,6277,6282,6286,6291,6297,6301,6305,6309,6312,6315,6321,6326,6333,6338,6347,6352,6358,6365,6367,6372,6383,6389,6396,6401,6408,6413,6420,6424,6433,6471,6477,6487,6493,6498,6502,6506,6509,6511,6514,6519,6532,6539,6546,6551,6557,6562,6568,6577,6611,6618,6622,6625,6630,6635,6639,6648,6650,6653,6657,6661,6664,6671,6672,6679,6683,6687,6692,6695,6700,6704,6709,6712,6713,6716,6719,6724,6725,6733,6736,6754,6776,6781,6784,6791,6794,6807,6811,6816,6821,6826,6827,6867,6873,6879,6883,6893,6900,6908,6913,6919,6925,6931,6935,6944,6950,6955,6959,6964,6967,6970,6986,6990,6995,6998,7001,7003,7007,7012,7015,7019,7023,7025,7030,7033,7037,7041,7046,7052,7053,7057,7060,7063,7065,7068,7081,7085,7090,7091,7094,7096,7101,7107,7113,7116,7119,7122,7130,7138,7153,7154,7158,7161,7164,7167,7177,7179,7190,7198,7203,7207,7211,7215,7225,7229,7235,7240,7242,7248,7253,7256,7258,7259,7263,7269,7275,7277,7282,7285,7290,7294,7298,7302,7306,7310,7316,7318,7321,7326,7331,7336,7339,7345,7348,7355,7359,7364,7369,7374,7379,7383,7386,7391,7395,7399,7403,7410,7415,7418,7423,7427,7432,7434,7438,7457,7458,7460,7463,7465,7468,7471,7474,7476,7479,7481,7483,7485,7487,7490,7492,7494,7498,7501,7504,7507,7511,7514,7517,7520,7525,7530,7534,7540,7543,7546,7548,7551,7591,7596,7599,7606,7609,7615,7622,7629,7639,7643,7648,7650,7658,7662,7667,7670,7677,7681,7686,7691,7693,7700,7702,7707,7712,7716,7725,7740,7746,7752,7759,7760,7763,7766,7772,7776,7985,7993,8000,8007,8028,8035,8042,8050,8057,8067,8074,8084,8091,8097,8103,8109,8111,8129,8233,8237,8241,8245,8249,8252,8260,8264,8292,8300,8309,8397,8420,8426,8430,8434,8437,8444,8448,8454,8462,8470,8477,8483,8488,8492,8499,8509,8515,8520,8526,8531,8538,8543,8548,8552,8557,8561,8565,8569,8573,8576,8581,8586,8594,8599,8608,8612,8615,8620,8624,8629,8632,8638,8641,8646,8650,8654,8655,8660,8665,8668,8673,8675,8681,8686,8691,8695,8700,8704,8708,8713,8718,8722,8727,8742,8747,8780,8783,8786,8789,8793,8797,8802,8807,8810,8813,8816,8819,8821,8825,8828,8831,8834,8839,8844,8847,8852,8853,8855,8858,8861,8864,8868,8872,8874,8878,8880,8884,8888,8891,8897,8902,8907,8916,8917,8921,8925,8929,8934,8939,8946,8959,8960,8966,8972,8979,8982,8987,8992,8994,9008,9011,9014,9018,9023,9027,9031,9035,9040,9043,9046,9053,9057,9061,9066,9071,9075,9078,9081,9086,9090,9095,9102,9105,9112,9117,9121,9129,9132,9137,9140,9142,9145,9151,9156,9171,9176,9192,9196,9202,9207,9213,9219,9222,9225,9229,9235,9242,9250,9263,9269,9273,9278,9284,9295,9303,9304,9305,9311,9319,9322,9328,9332,9335,9339,9346,9350,9355,9361,9366,9370,9375,9379,9382,9385,9392,9397,9400,9404,9410,9413,9418,9421,9424,9437,9441,9446,9451,9457,9466,9477,9481,9492,9495,9511,9516,9519,9523,9526,9532,9543,9684,9690,9387,8911,8228,8116,7756,6887,6829,5966,5335,5315,5300,4400,3840,12881,12893,12898,1180,1499,2188,2251,2256,2295,9462,9529,9750,9922,10087,10107,11089,11392,9605,9607,9612,9615,9619,9627,9633,9638,9640,9642,9669,9677,9681,9694,9697,9703,9707,9709,9711,9714,9716,9720,9726,9730,9733,9737,9740,9745,9752,9757,9767,9776,9778,9779,9784,9787,9789,9792,9796,9799,9803,9806,9811,9818,9820,9826,9827,9832,9836,9845,9847,9850,9852,9855,9858,9861,9862,9864,9868,9871,9875,9882,9886,9889,9892,9897,9899,9903,9907,9913,9916,9920,9926,9928,9930,9932,9936,9940,9943,9946,9950,9954,9957,9962,9964,9966,9973,9976,9977,9980,9981,9985,9986,9987,9989,10019,10022,10025,10027,10028,10055,10062,10189,10195,10197,10212,10220,10221,10224,10226,10229,10231,10232,10235,10428,10431,10434,10438,10440,10442,10443,10445,10448,10449,10455,10459,10466,10469,10471,10473,10474,10475,10476,10478,10481,10484,10486,10489,10493,10494,10496,10497,10499,10501,10502,10503,10508,10511,10514,10516,10518,10521,10524,10528,10529,10532,10160,10158,10156,10153,10149,10146,10138,10133,10132,10129,10126,10123,10119,10117,10116,10112,10111,10109,10101,10099,10097,10093,10090,10086,10084,10082,10078,10074,10070,10066,10045,10052,10041,10037,10036,10033,18596)
AND `a`.`userid` = '136'
GROUP BY `a`.`id`
ORDER BY `id` DESC, `id` DESC
LIMIT 15;
How can I improve the speed of that query?
Let me explain my tables:
mm_ads: Table where ads are stored in
mm_ads_fields_values: Table where options for ads are stored in.
Example:
Car is ad and having one row in table mm_ads. Car has following options: brand, model, color,... So Car ad has more than one row in table mm_ads_fields_values.
So if I search only cars with "black" color, the query will get first all IDs that have color option set to "black". Then I put these IDs to query.
Update:
Columns in table mm_ads_fields_values: id, aid, db_name, value
Sorry for my bad English..

Remove the LEFT JOIN and GROUP BY parts:
SELECT `a`.`title`, `a`.`askprice`, `a`.`picture`, `a`.`description`, `a`.`userid`, `a`.`id`
FROM `mm_ads` AS a
WHERE `a`.`status` = 1
AND `a`.`category` = '230'
AND `a`.`id` IN (…)
AND `a`.`userid` = '136'
ORDER BY
`id` DESC
LIMIT 15
Make sure that id is defined as a PRIMARY KEY.
I'm assuming the query is built by an ORM so recheck your model definition, the LEFT JOIN and GROUP BY are redundant here.
Update:
If you are searching for black cars, you can do it in a single query like this:
SELECT a.*
FROM mm_ads_fields_values afv
JOIN mm_ads a
ON a.id = afv.aid
WHERE afv.field = 'color'
AND afv.value = 'black'
ORDER BY
afv.aid DESC
LIMIT 15
Create a composite index on mm_ads_fields_values (field, value, aid).
Update 2:
To find black BMW:
SELECT a.*
FROM (
SELECT aid
FROM mm_ads_field_values afv
WHERE (field, value) = ('color', 'black')
OR (field, value) = ('model', 'BMW')
GROUP BY
aid
HAVING COUNT(*) = 2
ORDER BY
aid DESC
LIMIT 15
) af
JOIN mm_ads a
ON a.id = af.aid
ORDER BY
aid DESC

How to specify the parent query field from within a subquery in MySQL?

How do I specify the parent query field from within a subquery in MySQL?
For Example:
I have written a basic Bulletin Board type program in PHP.
In the database each post contains: id(PK) and parent_id(the id of the parent post). If the post is itself a parent, then its parent_id is set to 0.
I am trying to write a mySQL query that will find every parent post and the number of children that the parent has.
$query = "SELECT id, (
SELECT COUNT(1)
FROM post_table
WHERE parent_id = id
) as num_children
FROM post_table
WHERE parent_id = 0";
The tricky part is that the first id doesn't know that it should be referring to the second id that is outside of the subquery. I know that I can do SELECT id AS id_tmp and then refer to it inside the subquery, but then if I want to also return the id and keep "id" as the column name, then I'd have to do a query that returns me 2 columns with the same data (which seems messy to me)
$query = "SELECT id, id AS id_tmp,
(SELECT COUNT(1)
FROM post_table
WHERE parent_id = id_tmp) as num_children
FROM post_table
WHERE parent_id = 0";
The messy way works fine, but I feel an opportunity to learn something here so I thought I'd post the question.

How about:
$query = "SELECT p1.id,
(SELECT COUNT(1)
FROM post_table p2
WHERE p2.parent_id = p1.id) as num_children
FROM post_table p1
WHERE p1.parent_id = 0";
or if you put an alias on the p1.id, you might say:
$query = "SELECT p1.id as p1_id,
(SELECT COUNT(1)
FROM post_table p2
WHERE p2.parent_id = p1.id) as num_children
FROM post_table p1
WHERE p1.parent_id = 0";

You could try something like this
SELECT pt.id,
CountTable.Cnt
FROM post_table pt LEFT JOIN
(
SELECT parent_id,
COUNT(1) Cnt
FROM post_table
WHERE parent_id <> 0
GROUP BY parent_id
) CountTable ON pt.id = CountTable.parent_id
WHERE pt.parent_id = 0
To get back to your example, use the alias of the main table in the sub select
SELECT pt.id,
(SELECT COUNT(1) FROM post_table WHERE parent_id = pt.id)
FROM post_table pt
WHERE pt.parent_id = 0

Give the tables unique names:
$query = "SELECT a.id, (SELECT COUNT(1) FROM post_table b WHERE parent_id = a.id) as num_children FROM post_table a WHERE a.parent_id = 0";

The following syntax works in Oracle. Can you test if the same works in MYSQL too?
It is called scalar subquery in Oracle.
You would just need to alias the two tables differently to distinguish between them if you are using the same table twice.
sql> select empno,
2 (select dname from dept where deptno = emp.deptno) dname
3 from emp
4 where empno = 7369;
EMPNO DNAME
---------- --------------
7369 RESEARCH
sql> select parent.empno,
2 (select mgr from emp where empno = parent.empno) mgr
3 from emp parent
4 where empno = 7876;
EMPNO MGR
---------- ----------
7876 7788

Thanks Don. I had a nested query as shown below and a WHERE clause in it wasn't able to determine alias v1. Here is the code which isn't working:
Select
teamid,
teamname
FROM
team as t1
INNER JOIN (
SELECT
venue_id,
venue_scores,
venue_name
FROM venue
WHERE venue_scores = (
SELECT
MAX(venue_scores)
FROM venue as v2
WHERE v2.venue_id = v1.venue_id /* this where clause wasn't working */
) as v1 /* v1 alias already present here */
);
So, I just added the alias v1 again inside the JOIN. Which made it work.
Select
teamid,
teamname
FROM
team as t1
INNER JOIN (
SELECT
venue_id,
venue_scores,
venue_name
FROM venue as v1 /* added alias v1 here again */
WHERE venue_scores = (
SELECT
MAX(venue_scores)
FROM venue as v2
WHERE v2.venue_id = v1.venue_id /* Now this works!! */
) as v1 /* v1 alias already present here */
);
Hope this will be helpful for someone.

Parent query field within a subquery in MySQL 8.
I'm selecing games scores on the basis of username from tblgamescores using nested query.
SELECT
GameScoresID,
(SELECT Username FROM tblaccounts WHERE AccountID = FromAccountID) AS FromUsername,
(SELECT Username FROM tblaccounts WHERE AccountID = ToAccountID) AS ToUsername,
(SELECT Username FROM tblaccounts WHERE AccountID = WinAccountID) AS WinUsername,
(SELECT Username FROM tblaccounts WHERE AccountID = LossAccountID) AS LossUsername,
FromUserScore,
ToUserScore
FROM tblgamescores a
WHERE FromAccountID = (SELECT AccountID FROM tblaccounts WHERE Username = "MHamzaRajput");

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