I have to tables that I want to get all the results of both connect by a common cell. The problems is the second table only has some of records of the first table.
Table 1 forms
form_id, description, image,dept
Table 2 records
record_id, form_id, comments, added_date, done_date
If do a query like this:
SELECT * FROM form
JOIN records ON record.form_id = form.form_id
I do not get all of the forms because there is no record for that form. Is there away to do something like this? I would create a blank record for each form on in the records table, but I could not figure that out either.
This is a perfect application for a LEFT OUTER JOIN.
Example:
SELECT f.*, r.*
FROM form f
LEFT JOIN records r
ON r.form_id = f.form_id
ORDER BY f.description, r.added_date;
Use left join for these cases
SELECT * FROM form
LEFT JOIN records ON record.form_id = form.form_id
Please check which one u need --
LEFT OUTER JOIN :
Will include all records from Table Mentioned in Left Side and Matched Records from Right Side table, unmached record will be null
Ex :
SELECT *
FROM forms
LEFT JOIN records ON forms.form_id = record.form_id
FULL OUTER JOIN:
Will include all data from both table and unmatched will be null
Ex :
SELECT *
FROM forms
FULL OUTER JOIN records ON forms.form_id = record.form_id
Related
I have two tables.
Table A:
root_id, root_text
Table B:
word_id , word_text,root_text
Now Some of the records of Table B has root_texts which might not exist in Table A.
So for that I am trying to use left join.
select *
from A a , B b
where a.root_text=+b.root_text
I only get the records which has matching root_text.
If I use the new way
Select
*
from
A left join B on a.root_text= b.root_text
I get so many extra records. I am Using MySQL 5.6.1.7
UPDATE :
http://sqlfiddle.com/#!9/7b32a/2
Query I am running
select * from word_detail w left join roots r
on r.root_text =w.root
and w.surah_no=1
and w.verse_no=1
and w.word_no=1
What I am doing wrong ?
As in result you see so many records which are not needed. The filter verse_no , word_no not working.
Update
The issue was after the left join we have to use where
select * from word_detail w left join roots r
on r.root_text =w.root
where w.surah_no=1
and w.verse_no=1
and w.word_no=1
If you want all records from TableB that are not present in table A you should use this:
Select *
from
B left join A
on a.root_text= b.root_text
where
a.root_text is null
or if you want the opposite - all records from tableA that are not present on tableB:
Select *
from
A left join B
on a.root_text= b.root_text
where
b.root_text is null
btw, this is not a left join on MySQL:
select * from A a , B b where a.root_text=+b.root_text
but will result as a simple INNER JOIN
The += operator is not standard SQL, but specific to the Oracle RDBMS, so it will not work as expected on MySQL.
The LEFT JOIN syntax is correct, the "many extra records" stem from the data in your tables. You might want to use some sort of WHERE as a filter or an aggregate to group the result set to make it more managable.
Your first example is an inner join which explains why you are not getting as many results as when you are left joining. Left joining can also be thought of as a left outer join.
Im having a bit of difficulty with getting user information from one place to another.
There are 3 tables dbo.gr_usersource and dbo.gr_task and dbo.gr_user
In the dbo.gr_task table a column is filled with values that match entries in dbo.gr_usersource table that has another value that corresponds to the value in the dbo.gr_user table. You could call it a reference table between dbo.gr_task and dbo.gr_user tables.
My query looks like this;
select
dbo.gr_task.task_number
, dbo.gr_task.task_name
, dbo.gr_task.task_description
from dbo.gr_task
left join dbo.gr_user AS Handler
on dbo.gr_usersource.usersource_user = Handler.user_id
and dbo.gr_task.task_handler = dbo.gr.usersource.usersource.id
The last step would be to get the column user_name from table user when the join is working.
You have missed mediator table in your join so use as per below-
SELECT dbo.gr_task.task_number,dbo.gr_task.task_name, dbo.gr_task.task_description
FROM dbo.gr_task AS gt
LEFT JOIN dbo.gr_usersource gus ON gt.task_handler=gus.usersource.id
LEFT JOIN dbo.gr_user AS gu ON gus.usersource_user=gu.user_id;
Note: If you want only matching rows in all 3 tables then you should use normal join instead of left join.
This may work for you.
Note that there are no columns from your joined tables in your select list so left joins would have no impact on your result set.
Inner joins will filter your results set even if you bring back no columns, i.e., enforce the join condition to match rows in both tables.
SELECT
t.task_number
, t.task_name
, t.task_description
FROM dbo.gr_task t
INNER JOIN dbo.gr_usersource us
ON us.usersource.id = t.task_handler
INNER JOIN dbo.gr_user u
ON u.user_id = us.usersource_user
I've to add a notification module on an existing project.
My table structure is like on the pic.
Picture :
as you see on the picture every notification has a type and a releatedID.
Type 1 = reservation is cancelled, releated ID is the id on "reservations" table
Type 3 = account balance is under the given min. limit so releatedID is the id on "account_movements"
table
what I'm trying to do is a conditional join to avoid 2 different sql queries;
Get all notifications which are belong to the person
Get notification details from different tables based on "notification.Type"
So the question is can I do it in one query ?
Something like the following should work. Basically you specify which records in your notifications table join with records in your reservations table or your account_movements table when you join those in. Use a LEFT JOIN so that ALL of your notification records make it through, and only those records in the reservations table OR the account_movements that have a match make it through.
SELECT
n.id,
n.type,
n.companyid,
n.personid,
n.relatedid,
n.description,
r.details as reservation_details,
am.details as account_movement_details,
COALESCE(r.details, am.details) AS combined_detail
FROM
notifications n
LEFT OUTER JOIN reservations r ON
n.relatedid = r.id AND
n.type = 1
LEFT OUTER JOIN account_movements am ON
n.relatedid = am.id AND
n.type = 3
Here is a SQL FIDDLE with the solution as well.
I added in the COALESCE() just to show that since the JOINS are mutually exclusive, you can safely combine columns from your reservations table and your account_movements table into a single column without fear of missing or duplicating any data.
If you do a left join, you won't have to have any condition :
SELECT * FROM notifications n
LEFT JOIN reservations r ON n.releatedID = r.id
LEFT JOIN account_movements m ON m.releatedID = m.id
I am trying to select data from 3 separate tables, where 2 of those contains multiple rows of data. The sql query i am using is this, but i am experiencing that when i run it, if either taskdependees or tasksdependencies have zero result, the whole task is not showing.
SELECT t.*, GROUP_CONCAT(a.DependenciesId) as DiesId, GROUP_CONCAT(b.DependeesId) as DeesId FROM tasks t JOIN tasksdependencies a ON a.TasksId=t.TasksId JOIN taskdependees b ON b.TasksId=t.TasksId GROUP BY t.TasksId
What am I doing wrong in this query?
Use LEFT JOIN , inner join will give row if there is association is present in both tables while left will return the rows from left table even if they are not associated
SELECT t.*, GROUP_CONCAT(a.DependenciesId) as DiesId,
GROUP_CONCAT(b.DependeesId) as DeesId
FROM tasks t
LEFT JOIN tasksdependencies a ON a.TasksId=t.TasksId
LEFT JOIN taskdependees b ON b.TasksId=t.TasksId
GROUP BY t.TasksId
I'm trying to make something like a chart list and my actual query is like this:
SELECT
user.username,
songs.*,
albums.desc,
albums.release,
albums.name,
AVG(songrating.rating)
FROM
songs
INNER JOIN
user
ON
songs.userid=user.id
INNER JOIN
albums
ON
songs.albumid=albums.id
INNER JOIN
songrating
ON
songs.id=songrating.songid
GROUP BY
songrating.songid
it only shows entries with at least one rating entry, but I also want these without a rating
I tried to use it with if / case but it doesn't work (or I'm doing something wrong)
If I remove the avg etc, it works correctly.
It may be JOIN issue
The INNER JOIN keyword selects all rows from both tables as long as there is a match between the columns in both tables.
The LEFT JOIN keyword returns all rows from the left table (table1), with the matching rows in the right table (table2). The result is NULL in the right side when there is no match.
Try LEFT JOIN