Please help me with MySQL update to update the column with result returns from select itself.
For instance, I have two tables
TABLE user(
userid int,
groupid int
)
TABLE thread (
threadid int,
userid int,
sticky tinyint,
vip tinyint
)
Now I'm trying to achieve this with a single update query, but can't seem to do it. What I thought I should do is:
UPDATE user SET groupid=15 WHERE userid IN (SELECT userid FROM thread t LEFT JOIN user u ON u.userid=t.userid WHERE (t.sticky=1 AND t.vip=1) AND (u.groupid=11 OR u.groupid=14) GROUP BY t.userid);
but MySQL saids: #1093 - You can't specify target table 'user' for update in FROM clause
Please help me!
It can be done by generating a new table from left join of two tables and then update from the filtered result, syntax will be as follows:
UPDATE user AS nu
INNER JOIN
(SELECT u.userid, u.groupid
FROM thread t LEFT JOIN user u
ON u.userid=t.userid
WHERE (t.sticky=1 AND t.vip=1) AND
(u.groupid=11 OR u.groupid=14)
GROUP BY t.userid) AS my_table
ON nu.userid = my_table.userid
SET nu.groupid = 15;
Try using the following:
UPDATE user u2 SET u2.groupid=15 WHERE u2.userid IN (SELECT userid FROM thread t LEFT JOIN user u ON u.userid=t.userid WHERE (t.sticky=1 AND t.vip=1) AND (u.groupid=11 OR u.groupid=14) GROUP BY t.userid);
This should do the trick, hope it helps :)
update user1 u
left join thread1 t on t.userid = u.userid
where (t.sticky=1 AND t.vip=1) AND (u.groupid=11 OR u.groupid=14)
set u.groupid = 15
GROUP BY t.userid;
Use this
Is your desired query materially different from this...
UPDATE user u
JOIN thread t
ON t.userid = u.userid
SET groupid = 15
WHERE t.sticky = 1
AND t.vip = 1
AND u.groupid IN(11,14);
?
If so, then as Rockse suggests, consider providin proper DDLs (and/or an sqlfiddle) so that we can more easily replicate the problem, together with a corresponding desired result set.
You can add this before your query:
use yourdatabase;
yourdatabase is database name which includes user table
Related
I'm trying to assign an ID code by searching for the name.
update db.request r
set s.CreateByID = (
select r.ID
from db.user u
where r.NameCreateBy = u.Name
)
where r.ID in (23506);
How would I put a case clause for when I can't find the name in the user table?
The request table has the correct name of the person who created the request. But the createByID column is returning a code referring to another user. So I need to update createByID based on the user ID, disregarding the value shown in the request table.
you can use COALESCE if the subquery returns NULL amd set a value for example 0
update db.request r
set r.CreateByID = COALESCE((
select u.ID
from db.user u
where r.NameCreateBy = u.Name
),0)
where r.ID in (23506);
Consider using a JOIN inside the UPDATE statement, if you need to match fields between two tables:
UPDATE db.request r
INNER JOIN db.user u ON r.NameCreateBy = u.Name AND r.ID IN (23506)
SET s.CreateByID = COALESCE(r.ID, <substitution_value>);
I want to get all the data from the users table & the last record associated with him from my connection_history table , it's working only when i don't add at the end of my query
ORDER BY contributions DESC
( When i add it , i have only the record wich come from users and not the last connection_history record)
My question is : how i can get the entires data ordered by contributions DESC
SELECT * FROM users LEFT JOIN connections_history ch ON users.id = ch.guid
AND EXISTS (SELECT 1
FROM connections_history ch1
WHERE ch.guid = ch1.guid
HAVING Max(ch1.date) = ch.date)
The order by should not affect the results that are returned. It only changes the ordering. You are probably getting what you want, just in an unexpected order. For instance, your query interface might be returning a fixed number of rows. Changing the order of the rows could make it look like the result set is different.
I will say that I find = to be more intuitive than EXISTS for this purpose:
SELECT *
FROM users u LEFT JOIN
connections_history ch
ON u.id = ch.guid AND
ch.date = (SELECT Max(ch1.date)
FROM connections_history ch1
WHERE ch.guid = ch1.guid
)
ORDER BY contributions DESC;
The reason is that the = is directly in the ON clause, so it is clear what the relationship between the tables is.
For your casual consideration, a different formatting of the original code. Note in particular the indented AND suggests the clause is part of the LEFT JOIN, which it is.
SELECT * FROM users
LEFT JOIN connections_history ch ON
users.id = ch.guid
AND EXISTS (SELECT 1
FROM connections_history ch1
WHERE ch.guid = ch1.guid
HAVING Max(ch1.date) = ch.date
)
We can use nested queries to first check for max_date for a given user and pass the list of guid to the nested query assuming all the users has at least one record in the connection history table otherwise you could use Left Join instead.
select B.*,X.* from users B JOIN (
select A.* from connection_history A
where A.guid = B.guid and A.date = (
select max(date) from connection_history where guid = B.guid) )X on
X.guid = B.guid
order by B.contributions DESC;
So, I've got two tables: users and tasks;
users:
user_id username password first_name last_name isAdmin
tasks:
task_id name description assessment assigned_user_id fk creator_id fk created_on last_modified status
What I want to do is replace assigned_user_id and creator_id with first_name + last_name from users table. So I execute the following query:
SELECT `task_id`, `description`,`assessment`,
(SELECT CONCAT(`first_name`, ' ',`last_name`) WHERE `Tasks`.`assigned_user_id` = `Users`.`user_id`) AS assigned_user,
(SELECT CONCAT(`first_name`, ' ',`last_name`) WHERE `Tasks`.`creator_id`=`Users`.`user_id`) AS creator_user,
`created_on`,`last_modified`,`status`
FROM `Tasks`
LEFT JOIN `Users`
ON Tasks.assigned_user_id = Users.user_id
OR Tasks.creator_id = Users.user_id
WHERE task_id=2
The problem is that it returns 2 rows. One is with assigned_user_id null and filled creator_id and the other is the other way around:
task_id description assessment assigned_user creator_user created_on last_modified status
2 SHA SA PII LI 24 NULL Petyo Chuliuv 2016-07-22 2016-07-22 1
2 SHA SA PII LI 24 Gosho Toshov NULL 2016-07-22 2016-07-22 1
Question is: How to return a single row with assigned_user and creator_user filled and where I did wrong? Thanks in advance!
I tested this on SQL Server and reproduced the same issue as you so hopefully I can be of help.
When I did the test the two SELECT CONCAT statements were using the same user_id both times. So the issue seems that it is not checking for both ids at once but both ids at separate times. So if I were to use your example it first uses Petyo's id in both of the SELECT CONCAT statements (only filling the creator_user role so the other one becomes false) and then it uses Gosho's id in both of the SELECT CONCAT statements which also only fills one field (the assigned_user field) and making the other one null.
So what you need to do is JOIN the Users table again. One for the assigned, one for the create. Something like this...
SELECT `task_id`, `description`,`assessment`,
(SELECT CONCAT(`U1.first_name`, ' ',`U1.last_name`)) AS assigned_user,
(SELECT CONCAT(`U2.first_name`, ' ',`U2.last_name`)) AS creator_user,
`created_on`,`last_modified`,`status`
FROM `Tasks`
LEFT JOIN `Users` U1
ON Tasks.assigned_user_id = U1.user_id
LEFT JOIN `Users` U2
ON Tasks.creator_id = U2.user_id
WHERE task_id=2
Before you had an OR. It does not look at one side, look for the id, then look at the other one, look for the id, then use it at once. It is exactly that. If the current user_id it is looking for happens to be one of those two then it uses that single user_id.
You need to join to your users table twice and alias them...
Somethin like...
SELECT `task_id`, `description`,`assessment`,
(SELECT CONCAT(`assignedUsers.first_name`, ' ',`assignedUsers.last_name`) AS assigned_user,
(SELECT CONCAT(`createdUsers.first_name`, ' ',`createdUsers.last_name`) AS creator_user,
`created_on`,`last_modified`,`status`
FROM `Tasks`
LEFT JOIN `Users` assignedUsers ON Tasks.assigned_user_id = assignedUsers .user_id
LEFT JOIN `Users` createdUsers ON Tasks.creator_id = createdUsers .user_id
WHERE task_id=2
Since you have two foreign keys and you want to fetch the corresponding data you just have to INNER JOIN the users table twice.
You used LEFT JOIN which will fetch all the data from the first table,in your case tasks, even if no match is found in the second table (in your case this did not made any difference but in cases where an id is not set or the user does not exist anymore maybe this is a problem that is up to you to decide...) and you also used OR in the JOIN conditions which resulted in duplicate tasks in the results.
So you must INNER JOIN twice.One time to get the assigned user and one to get the creator.
Havent tested but this should work :
SELECT t.`task_id`, t.`description`,t.`assessment`,
CONCAT(u1.`firstname`,' ',u1.`lastname`) as creator,
CONCAT(u2.`firstname`,' ',u2.`lastname`) as assigned_user,
t.`created_on`,t.`last_modified`,t.`status`
FROM `tasks` t
INNER JOIN `users` u1 ON t.creator_id=u1.id
INNER JOIN `users` u2 ON t.assigned_user_id=u2.id
WHERE t.`task_id`=2
Thank you all guys but I fixed it by doing:
SELECT `task_id`, `description`,`assessment`,
(SELECT CONCAT(`first_name`, ' ', `last_name`)
FROM `Users`
WHERE `Tasks`.`assigned_user_id` = `Users`.`user_id`) AS assigned_user,
(SELECT CONCAT(`first_name`, ' ', `last_name`)
FROM `Users`
WHERE `Tasks`.`creator_id`=`Users`.`user_id`) AS creator_user,
`created_on`,`last_modified`,`status`
FROM `Tasks`
WHERE task_id=3
I just added FROM Users and WHERE clauses in each inner SELECT,
so I didn't have to do any joins... As always it was way more simple than I thought. Thanks again, much appreciated!
What I want to do is to set every patient its unique patient code which starts with 1 and it's not based on row id. Id only specifies order. Something like this:
patient_id patient_code
2 1
3 2
4 3
This is my query:
UPDATE patients p1
SET p1.patient_code = (
SELECT COUNT( * )
FROM patients p2
WHERE p2.patient_id <= p1.patient_id
)
But it is throwing error:
#1093 - You can't specify target table 'p1' for update in FROM clause
I found this thread: Mysql error 1093 - Can't specify target table for update in FROM clause.But I don't know how to apply approved answer this to work with subquery WHERE which is necessary for COUNT.
UPDATE
patients AS p
JOIN
( SELECT
p1.patient_id
, COUNT(*) AS cnt
FROM
patients AS p1
JOIN
patients AS p2
ON p2.patient_id <= p1.patient_id
GROUP BY
p1.patient_id
) AS g
ON g.patient_id = p.patient_id
SET
p.patient_code = g.cnt ;
I found working solution, but this is just workaround:
SET #code=0;
UPDATE patients SET patient_code = (SELECT #code:=#code+1 AS code)
Try this,
UPDATE patients p1 INNER JOIN
(
SELECT COUNT(*) as count,patient_id
FROM patients
group by patient_id
)p2
SET p1.patient_code=p2.count
WHERE p2.patient_id <= p1.patient_id
SQL_LIVE_DEMO
Thanks to Mari's answer I found a solution to my similar problem. But I wanted to add a bit of an explanation which for me at first wasn't too clear from his answer.
What I wanted to do would have been as simple as the following:
UPDATE my_comments AS c
SET c.comment_responses = (
SELECT COUNT(c1.*) FROM my_comments AS c1
WHERE c.uid = c.parent_uid
);
Thanks to Mari I then found the solution on how to achieve this without running into the error You can't specify target table 'p1' for update in FROM clause:
UPDATE my_comments AS c
INNER JOIN (
SELECT c1.parent_uid, COUNT(*) AS cnt
FROM my_comments AS c1
WHERE c1.parent_uid <> 0
GROUP BY c1.parent_uid
) AS c2
SET c.comment_responses = c2.cnt
WHERE c2.parent_uid = c.uid;
My problems before getting to this solution were 2:
the parent_uid field doesn't always contain an id of a parent which is why I added the WHERE statement in the inner join
I didn't quite understand why I would need the GROUP BY until I executed the SELECT statement on it's own and the answer is: because COUNT groups the result and really counts everything. In order to prevent this behavior the GROUP BY is needed. In my case I didn't have to group it by uid though but the parent_uid to get the correct count. If I grouped it by uid the COUNT would always be 1 but the parent_uid existed multiple times in the result. I suggest you check the SELECT statement on it's own to check if it's the result you expect before you execute the full UPDATE statement.
I have the following Mysql select that returns all the duplicate email addresses in my table.
SELECT users.FirstName, `Surname`, users.email1
FROM users
INNER JOIN (
SELECT email1
FROM users
GROUP BY email1
HAVING count(email1) > 1) dup ON users.email1 = dup.email1
ORDER BY users.email1
This works great, what I wish to do now is update a field called users.DupEmail with "YES" but I am unsure how to do this. I have tried putting an update line to replace the select, but I am clearly getting it wrong as I am back here asking for help.
Can anyone help please?
You can just use the multiple-table UPDATE syntax with a self-join:
UPDATE users AS u1
JOIN users AS u2 USING (email1)
SET u1.DupEmail = 'YES'
WHERE NOT u1.id = u2.id; -- use your primary key here
The following script must solve your problem -- be safe and use the SELECT to test results before aplying the update:
-- SELECT FirstName, Surname, email1
-- FROM users
UPDATE users
SET DupEmail = 1
WHERE u0.email1 IN (
SELECT u1.email1
FROM users u1
GROUP BY u1.email1
HAVING COUNT(*) > 1
)