Can you please check this mysql query and maybe help with what's wrong with it?
When I run it through mysql as my host i get this error:
#1248 - Every derived table must have its own alias
Here is the code:
mysql_query("
SELECT COUNT(*)
FROM
(
(SELECT 1 as sort_col,id,pic0 FROM `cronjob_reloaded` WHERE id IS NOT NULL AND id LIKE '%car%')
UNION
(SELECT 2 as sort_col,id,pic0 FROM `cronjob_reloaded` WHERE id IS NOT NULL AND category IN ('bmw'))
ORDER BY sort_col
)
")
Ty!
PS. I have posted an unclear question some time ago, can a admin please delete that one? And sorry for any inconvenience. The question is here
As the error says, derived tables must be aliased.
SELECT COUNT(*)
FROM
(
(SELECT 1 as sort_col,id,pic0 FROM `cronjob_reloaded` WHERE id IS NOT NULL AND id LIKE '%car%')
UNION
(SELECT 2 as sort_col,id,pic0 FROM `cronjob_reloaded` WHERE id IS NOT NULL AND category IN ('bmw'))
ORDER BY sort_col
) q /* I added the alias "q" */
Related
I have a table. Table has structure of id, name, color, product_id.
And the table has multiple rows with the same product_id.
With SQL query from PHP file - I would like to choose only one, the oldest, row. (The first one that was added to the current table).
What query should I use or approach?
Thank you!
Just making up a bit of mockup data ... Note the notes I put in. And I trust it's a newer version of MySQL, as the older ones did not support ROW_NUMBER() OVER() .
Here goes:
WITH
-- input ... you *need* a timestamp to identify the oldest ---
indata(id, name, color, product_id,ts) AS (
SELECT 1,'Arthur','blue' ,42,TIMESTAMP'2021-01-31 17:45:00'
UNION ALL SELECT 1,'Arthur','blue' ,42,TIMESTAMP'2021-01-31 17:50:00'
UNION ALL SELECT 1,'Arthur','blue' ,42,TIMESTAMP'2021-01-31 17:55:00'
UNION ALL SELECT 1,'Arthur','blue' ,42,TIMESTAMP'2021-01-31 18:00:00'
UNION ALL SELECT 2,'Ford' ,'red' ,42,TIMESTAMP'2021-01-31 17:45:00'
UNION ALL SELECT 2,'Ford' ,'blue', 42,TIMESTAMP'2021-01-31 17:50:00'
UNION ALL SELECT 2,'Ford' ,'green',42,TIMESTAMP'2021-01-31 17:55:00'
UNION ALL SELECT 2,'Ford' ,'cyan' ,42,TIMESTAMP'2021-01-31 18:00:00'
)
,
-- select all, plus a rank, on which you will filter outside ..
with_rank AS (
SELECT
*
, ROW_NUMBER() OVER(PARTITION BY id ORDER BY ts) AS rnk
FROM indata
)
SELECT
id
, name
, color
, product_id
, ts
FROM with_rank
WHERE rnk = 1
id|name |color|product_id|ts
1|Arthur|blue |42 |2021-01-31 17:45:00
2|Ford |red |42 |2021-01-31 17:45:00
One method is a correlated subquery:
select t.*
from t
where t.id = (select min(t2.id)
from t t2
where t2.product_id = t.product_id
);
This assumes that id is incrementing with each insertion. If not, you have no way of knowing what the "oldest" row is. SQL tables represent unordered sets, so there is no "oldest" row unless a column contains that information.
SELECT * FROM TableName WHERE product_id = ProductID ORDER BY product_id LIMIT 1;
Two tables, with a left join. For ease table 1 and table 2.
Table 1 contains a list of people and their current status, table 2 is all of their "invites". All im trying to do as part of the join is show in a list all the current "people" and then the LATEST invite status (from table 2) so return a single row from table 2.
I have everything working... but its duplicating for example if a person has had multiple invites it will put them twice on the list. I just want to limit it to
$sql = "SELECT table1.fieldname as table1fielname table2.fieldname [more fields]
FROM xxx
LEFT JOIN xxx on table1.sharedid=table2.sharedid
WHERE XXX LIMIT 1 ";`
Obvioulsy the limit 1 doesnt do what its supposed to. I have tried adding additional select statements in brackets but being honest it just breaks everything and im not an expert at all.
I'm not an expert too but I'll try. Have you tried to use DISTINCT?
For exemple:
SELECT DISTINCT column_name1,column_name2
FROM table_name; [...]
It normally delete double matches.
Here are the links:
http://www.w3schools.com/sql/sql_distinct.asp
https://www.techonthenet.com/oracle/distinct.php
Give example data. And use good table and column names. For example:
(this returns all rows that satisfy the join):
WITH people(ppl_id,ppl_name,status) AS (
SELECT 1,'Arthur','active'
UNION ALL SELECT 2,'Tricia','active'
), invites(ppl_id,inv_id,inv_date) AS (
SELECT 1,1, DATE '2017-01-01'
UNION ALL SELECT 1,2, DATE '2017-01-07'
UNION ALL SELECT 1,3, DATE '2017-01-08'
UNION ALL SELECT 2,1, DATE '2017-01-01'
UNION ALL SELECT 2,2, DATE '2017-01-08'
)
SELECT
*
FROM people
JOIN invites USING(ppl_id)
ORDER BY 1
;
ppl_id|ppl_name|status|inv_id|inv_date
1|Arthur |active| 1|2017-01-01
1|Arthur |active| 3|2017-01-08
1|Arthur |active| 2|2017-01-07
2|Tricia |active| 2|2017-01-08
2|Tricia |active| 1|2017-01-01
But we want only 'Arthur' with '2017-01-08' and 'Tricia' with '2017-01-08'.
With any database that supports ANSI 99, you could try with a temporary table containing the newest invitation date per "people id", and join that temporary table with the invitations table. We call that table newest_invite_date, and, apparently, it does what we expect it to do:
WITH people(ppl_id,ppl_name,status) AS (
SELECT 1,'Arthur','active'
UNION ALL SELECT 2,'Tricia','active'
), invites(ppl_id,inv_id,inv_date) AS (
SELECT 1,1, DATE '2017-01-01'
UNION ALL SELECT 1,2, DATE '2017-01-07'
UNION ALL SELECT 1,3, DATE '2017-01-08'
UNION ALL SELECT 2,1, DATE '2017-01-01'
UNION ALL SELECT 2,2, DATE '2017-01-08'
), newest_invite_date(ppl_id,inv_date) AS (
SELECT ppl_id,MAX(inv_date)
FROM invites
GROUP BY ppl_id
)
SELECT
people.ppl_id
, people.ppl_name
, people.status
, newest_invite_date.inv_date
FROM people
JOIN newest_invite_date USING(ppl_id)
ORDER BY 1
;
ppl_id|ppl_name|status|inv_date
1|Arthur |active|2017-01-08
2|Tricia |active|2017-01-08
Is this what you were looking for?
Happy playing ...
Marco the Sane
I have the following code in PHP:
SELECT (
SELECT (
SELECT `forum_posts.id`,`forum_posts.author`,`forum_posts.author_id`, `forum_boards.date`, MIN(`forum_posts.date`) FROM `forum_posts`
WHERE `parent` IN
(SELECT `id` FROM `forum_boards` WHERE `parent`="'.Oflow(intval((isset($_GET['id']) ? $_GET['id'] : '0'))).'")
INNER JOIN `forum_boards`
ON `forum_boards.id`=`forum_posts.id`
ORDER BY `update_date` DESC
LIMIT 1
GROUP BY `parent`;
) ORDER BY `order_large`,`order`;
) UNION (
SELECT `name`,`id`,`info`,`parent_name` FROM `forum_boards` WHERE `parent`="'.Oflow(intval((isset($_GET['id']) ? $_GET['id'] : '0'))).'" ORDER BY `order_large`,`order
)
This is a script to get a list of boards and posts in a forum system. What it's supposed to do is get data from a table "boards" and "posts". It then tries to find the most recent post in the sub-board of the board currently being viewed. Then, it tries to join the "parent" and board "id" togeather, in order that the columns can be matched and the posts be sorted accordingly. Finally, a UNION is performed to combine the newly found and ordered posts with the actual forum data.
The error:
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'INNER JOIN forum_boards ON forum_boards.id=forum_posts.id ORDER BY' at line 7
The problem is, it don't work! I've double checked every column and table name, and they all exist. This is a very "alpha" code, so if you have any efficiency tips that's be great.
You can't INNER JOIN in the WHERE clause which is what your query is trying to do
SELECT (
SELECT (
SELECT `forum_posts.id`,`forum_posts.author`,`forum_posts.author_id`, `forum_boards.date`, MIN(`forum_posts.date`) FROM `forum_posts`
WHERE `parent` IN
(SELECT `id` FROM `forum_boards` WHERE `parent`="'.Oflow(intval((isset($_GET['id']) ? $_GET['id'] : '0'))).'")
INNER JOIN `forum_boards` ## This is effectively JOINing within a WHERE clause
ON `forum_boards.id`=`forum_posts.id`
ORDER BY `update_date` DESC
LIMIT 1
GROUP BY `parent`;
) ORDER BY `order_large`,`order`;
) UNION (
SELECT `name`,`id`,`info`,`parent_name` FROM `forum_boards` WHERE `parent`="'.Oflow(intval((isset($_GET['id']) ? $_GET['id'] : '0'))).'" ORDER BY `order_large`,`order
)
You might need to rethink your query a little bit.
I have a sample database like this, in which, id is always unique, but the user_id is not unique.
id,user_id,message,msg_datetime
111,u1, msg from u1,time present here
112,u2, msg from u2,time present here
113,u3, msg from u3,time present here
114,u2, msg from u2,time present here
115,u7, msg from u7,time present here
116,u2, msg from u2,time present here
117,u1, msg from u1,time present here
118,u5, msg from u5,time present here
so i want to grab only those unique users who have messaged and order them in DESC by msg_datetime.
This is the query i have.
select id,DISTINCT user_id,msg_datetime ORDER BY msg_datetime DESC but i am getting an error as:
You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'DISTINCT. any help here? what is the correct syntax for what i am trying to achieve?
I want to show only one entry for each user, it does not matter which ID i am showing but only 1 per user.
If you don't care which record with the same user_id query should return, then
SELECT id,user_id,msg_datetime FROM table_1 GROUP BY user_id ORDER BY msg_datetime DESC
If you want to display, for instance, the last record for each user, you need
SELECT a.user_id, a.last_time, b.id
FROM
(SELECT user_id, MAX(msg_datetime) as last_time
FROM table1)a
INNER JOIN table1 b ON (b.user_id = a.user_id AND b.msg_datetime = a.last_time)
ORDER BY a.last_time;
SELECT syntax:
SELECT (fieldlists)
FROM (table)
[WHERE (conditions)]
ORDER BY (something)
You kindof forgot to say which table you want the data from.
You misunderstand how DISTINCT works. It works on rows not fields. What you want is a groupwise maximum, also known as greatest-n-per-group.
Here's one way to do it in MySQL:
SELECT id, user_id, message, msg_datetime
FROM (
SELECT
id, user_id, message, msg_datetime,
#rn := CASE WHEN #prev_user_id = user_id
THEN #rn + 1
ELSE 1
END AS rn,
#prev_user_id := user_id
FROM (SELECT #prev_user_id := NULL) vars, Table1 T1
ORDER BY user_id, msg_datetime DESC
) T2
WHERE rn = 1
ORDER BY msg_datetime
Right, another question on queries (there must be a syntax guide more helpful than mySQL's manual, surely?)
I have this query (from another helpful answer on SO)...
SELECT DATE_FORMAT(`when`, '%e_%c_%Y')date, COUNT(`ip`) AddressCount FROM `Metrics` WHERE `ID` = '1' GROUP BY DATE(`when`)
I now want to do a similar query to get unique/distinct results for the IPs... i.e. unique visitors per date. My query was this...
SELECT DATE_FORMAT(`when`, '%e_%c_%Y')date, COUNT(distinct `ip`) AddressCount FROM `Metrics` WHERE `ID` = '1' GROUP BY DATE(`when`)
However, that returns a repetition of dates, though different quantities of Addresscount...
date AddressCount
29_6_2009 1
30_6_2009 1
29_6_2009 1
30_6_2009 1
29_6_2009 1
NULL 1
15_5_2009 1
14_5_2009 2
NULL 3
14_5_2009 4
15_5_2009 1
26_6_2009 1
29_6_2009 1
26_6_2009 1
15_5_2009 1
26_6_2009 1
29_6_2009 1
Any ideas on where I'm going wrong?
Your group by will need to match the data you're selecting, so this should work:
SELECT DATE_FORMAT(`when`, '%e_%c_%Y')date, COUNT(distinct `ip`) AddressCount FROM `Metrics` WHERE `ID` = '1' GROUP BY date
Try
SELECT DATE_FORMAT(when, '%e_%c_%Y')date, COUNT(distinct ip) AddressCount FROM Metrics WHERE ID = '1' GROUP BY date(when)
You might have run into some bugs when using reserved words in MySQL