I have 3 tables; CASES, USERS and USER_META. For this issue you need to know that the USER_META table has 3 columns; user_id, meta_key and meta_value
Each user is associated with many CASES and each USER is associated with many USER_META
My current query is like this
SELECT CASES.*, USERS.*, USER_META.*
FROM CASES
JOIN USERS ON USERS."user_id" = CASES."user_id"
JOIN USER_META ON USER_META_"user_id" = USERS."user_id"
The problem with this approach is that each USER has A LOT of USER_META so my result set has too many rows. How can I rewrite this query so that I can select only the USER_META where the USER_META."meta_key" is equal to a certain value yet still get the result if they do not have this USER_META."meta_key" set yet
For example:
SELECT CASES.*, USERS.*, USER_META.*
FROM CASES
JOIN USERS ON USERS."user_id" = CASES."user_id"
JOIN USER_META ON USER_META_"user_id" = USERS."user_id"
WHERE USER_META."meta_key" = 'my_key'
This would work great but not all users have a value of "my_key" in the "meta_key" column and we still need to view their CASE. For users that do not have the "meta_key" the result should just return the CASE and USER columns.
How can I rewrite this query so it gets the result for both users with this meta_key and without?
Thanks, I hope this makes sense.
I would use a LEFT JOIN
SELECT CASES.*, USERS.*, USER_META.*
FROM CASES
JOIN USERS ON USERS."user_id" = CASES."user_id"
LEFT JOIN USER_META ON USER_META."user_id" = USERS."user_id" AND USER_META."meta_key" = ?
you need to use OUTER JOIN with the table that may have no results. In Oracle, use (+) near to the field name of the join sentence with this table. This link may help you: http://download.oracle.com/docs/cd/B28359_01/server.111/b28286/queries006.htm
Related
I have a database with 2 tables in it one is 'enlistments' and the other one is 'users'. In the enlistments table I have a user_id and in the users table I have a name. I want to get the name of the user which belongs to the id.
I know I need to do this with an inner join like this:
SELECT enlistments.round_id, users.name
FROM enlistments
INNER JOIN users
ON enlistments.user_id=users.name
WHERE enlistments.activity_id = 1;
However I get this error: Warning: #1292 Truncated incorrect DOUBLE value
I did some research and found out it has to do with comparing an int with a string but I don't know how to solve the problem.
This is how my database looks like
join on is the condition you use to join the tables. Here it's enlistments.user_id=users.id.
select e.round_id
,u.name
from enlistments e join users u on u.id = e.user_id
where activity_id = 1
round_id
name
1
test2
Fiddle
To validate and be sure you are pulling back the exact data desired, I usually provide aliases for each column brought back and make sure to bring back the join columns also. It's good practice to label where the columns returned originated.
SELECT
Enlistments.UserID as Enlistments_UserID,
Users.ID as Users_ID,
enlistments.round_id as Enlistments_RoundID,
users.name as Users_Name
FROM enlistments
INNER JOIN users
ON enlistments.user_id=users.id
WHERE enlistments.activity_id = 1;
SELECT EN.round_id, US.name
FROM enlistments EN
INNER JOIN users US
ON US.name= CAST(EN.user_id AS VARCHAR)
WHERE EN.activity_id = 1
What you are needing is the function cast that can convert any kind of data into another, so you'll pass your integer value as the first argument followed by "AS '%DATATYPE'" where %DATATYPE is the kind of data you want to achieve.
In your case:
SELECT CAST(123456 AS VARCHAR)
-- RETURNS : '123456'
Anyway, I’m not sure that you can be able to join these two tables with the join you are using.
For more help please share some data.
This is task table:
This is user table:
I want to select user tasks.
I would give from backend ("given_to_user) id.
But The thing is I want that SELECTED data would have usernames instead of Id which is (created_by_user and given_to_user).
SELECTED table would look like this.
Example:
How to achieve what I want?
Or maybe I designed poorly my tables that It is difficult to select data I need? :)
task table has to id values that are foreign keys to user table.
I tried many thinks but couldn't get desired result.
You did not design poorly the tables.
In fact this is common practice to store the ids that reference columns in other tables. You just need to learn to implement joins:
SELECT
task.id, task.title, task.information, user.usename AS created_by, user2.usename AS given_to
FROM
(task INNER JOIN user ON task.created_by_user = user.id)
INNER JOIN user AS user2 ON task.created_by_user = user2.id;
Do you just want two joins?
select t.*, uc.username as created_by_username,
ug.username as given_to_username
from task t left join
users uc
on t.created_by_user = uc.id left join
users ug
on t.given_to_user = ug.id;
This uses left join in case one of the user ids is missing.
I'm having trouble doing the following query. The idea is that I have two tables Stores and Users. In Stores I have the columns store_owners and store_last_modified, both values are integer that are related to the id of dbo.Users. How I can display the name that is stored in users related to the two columns. Like that:
select stores.name , users.name as name_store_owner , users.name as name_store_last_modified
from stores
LEFT JOIN users ON stores.store_owners=users.id (related to name_store_owner)
LEFT JOIN users ON stores.store_last_modified=users.id (related to name_store_last_modified)
How do I do that?
Thank you in advance.
You need to give the tables aliases, so you can refer to the same table twice in the from clause. In addition, you need to refer to the right table (users not stores):
select s.name, uo.name as name_store_owner, um.name as name_store_last_modified
from stores s left join
users uo
on s.store_owners = uo.id left join
users um
on s.store_last_modified = um.id
It appears that the condition can be checked without referring the table twice.
select * from
stores s
left join
users u on u.id = s.store_owners
and u.id = s.store_last_modified
From your question it appears that user id (id) should match with both the columns in the stores table for a single row.
I'm trying to write a query in oracle SQL, first I am trying to edit a profile, so I want to change the institution that the user previously select it, but for that I must get all the institutions from a table named institution (id_institution, name_institution),
select user.user_name, institution.name_institution from user
inner join institution_has_user on user.id_user = institution_has_user.user_id_user
inner join institution on institution_has_user.institution_id_institution = institution.id_institution
where user = 'george';
But all I get It is the data that he register, and I want all the institutions, so I can fill a select html, just for editing purposes
If you want to return all the institutions from your above query, then you'll need to use an OUTER JOIN and move your WHERE criteria to your JOIN. This will however return NULL records for the user name field where there aren't any matches which might not be what you're looking for:
select distinct user.user_name, institution.name_institution
from institution
left join institution_has_user on institution_has_user.institution_id_institution = institution.id_institution
left join user on user.id_user = institution_has_user.user_id_user
and user.user_name = 'george';
Perhaps an easier alternative solution, just run two queries -- it should be perfectly fine to create a drop down list from a single select statement:
select name_institution
from institution
I am using SQL Server 2005. I have three tables - Users, Groups, and GroupUsers. GroupUsers contains the two PKs for a many-to-many relationship.
I have a view to get all the user information for a group as follows:
SELECT * FROM GroupUsers JOIN Users ON GroupUsers.UserID = Users.UserId
I want to create the inverse of this view - I want a list of all of the users NOT attached to a specific group. The following query would accomplish this:
SELECT * FROM Users WHERE UserID NOT IN
(SELECT UserID FROM GroupUsers WHERE GroupID=#GroupID)
However I don't want to have to specify the group, I want to know how to turn this into a view that joins the GroupID and then the UsersID and all the user info, but only for non-attached users.
I'm not sure how to do this, maybe something with the EXCEPT operator?
UPDATE:
I think this is my solution, unless someone comes up with something better:
SELECT
G.GroupId,
U.*
FROM
Groups G
CROSS JOIN
Users U
WHERE
U.UserId NOT IN
(
SELECT
UserId
FROM
GroupUsers
WHERE
GroupId=G.GroupId
)
You can use a left outer join to grab all of the users, then, blow away any user where there's a group attached. The following query will give you just the list of users where there's no group to be had:
select
u.*
from
users u
left outer join groupusers g on
u.userid = g.userid
where
g.userid is null
If you want to find all users not in a particular group:
select
u.*
from
users u
left outer join groupusers g on
u.userid = g.userid
and g.groupid = #GroupID
where
g.userid is null
This will only exclude the users in that particular group. Every other user will be returned. This is because the groupid condition was done in the join clause, which limits the rows joined, not returned, which is what the where clause does.
If I understand it correctly, you will have to do a cartersian result of users & groups and reduce the result derived from GroupUsers.
That will give you records of users which do not have any groups attached to it.
I apologize if I didn't understand the question correctly.
EDIT: Cartesian result will give you users * groups. You will have to subtract GroupUsers from it. I am sorry, I do not have SQL ready for it & can't try it out at this point.
I couldn't figure out how to get previous version to work via active record, got some of the way there but had to write an SQL in statement. I believe this also accomplishes the same thing.
SELECT * FROM Users WHERE UserID NOT IN
(SELECT U.UserID FROM GroupUsers AS G, Users as U WHERE G.UserID <> U.UserID)
Couldn't test however this query in rails worked just fine:
# Gets Pre-Clients. Has client information but no project attached
Contact.joins(:client).includes(:projects => :primary_contact).
where("contacts.id NOT IN (select contacts.id from contacts,
projects where projects.primary_contact_id = contacts.id)")
Thanks for the post got me 90% of the way there.