This is a very basic question, I apologize if someone has already asked this question..
I have a main table called 'item'. It has all the item(s) related information such as catalog,description,avail,price etc
I also have another table called 'activelisting' which only have one column 'catalog'.
Now I want to pull 'catalog','description', and 'avail' from 'item' table based on 'catalog' exists in 'activelisting' table.
or another words everything from 'activelisting' table and matching records from 'item' table.
I have researched it a lot but I am unable to find working query. I am using the following query..
SELECT t1.catalog, t1.description, t1.avail
FROM item t1
LEFT JOIN activelisting t2
ON t1.`Catalog` = t2.`Catalog`;
any help would be appreciated...
Try using INNER JOIN instead of LEFT JOIN. INNER JOIN will guarantee that the value being joined on exists in both tables.
SELECT i.catalog, i.description, i.avail
FROM item i
INNER JOIN activelisting a ON i.catalog = a.catalog
LEFT JOIN will return all results in the left table, item and if there is not a row in activelisting with the same catalog then it will just return NULL for those columns. You are not currently selecting the potential NULL columns, so your current result should basically just be all of the entries in item.
SELECT t1.catalog, t1.description, t1.avail FROM item t1 RIGHT OUTER JOIN activelisting t2 ON t1.Catalog = t2.Catalog;
OR
SELECT t1.catalog, t1.description, t1.avail FROM activelisting t2 LEFT OUTER JOIN item t1 ON t1.Catalog = t2.Catalog;
The first one for good visualizer. You have to use outer join just because you take all catalogs from activlisting table and matched catalog from item table.
Second one for better understanding.
Related
I would like to get data from 2 mysql tables.
Table tbl_1:
Table tbl_2:
I tried this:
SELECT `tbl_2`.*
FROM `tbl_1`
LEFT JOIN `tbl_2` ON `tbl_1`.invoiceID = `tbl_2`.invoiceID
WHERE `tbl_1`.customerID = "463";
My result:
The results looks good but not perfect.
I get many null rows which are not be in my result.
only the first both rows should be in the result.
Where is my fault?
The LEFT JOIN keyword returns all records from the left table (tbl_1), and the matching records from the right table (tbl_2).
Maybe you should try 'INNER JOIN' instead of 'LEFT JOIN'?
The LEFT JOIN keyword returns all records from the left table tbl_1, and the matching records from the right table tbl_2. So change the order of the tables
SELECT `tbl_2`.*
FROM `tbl_2`
LEFT JOIN `tbl_1` ON `tbl_1`.invoiceID = `tbl_2`.invoiceID
WHERE `tbl_1`.customerID = '463';
Sir,
You have two tables (Table1 and Table2) and there is a COMMON column called invoiceID in both your tables. So if you want to select some columns from these two tables for a given CUSTOMERID:
SELECT Table1.*, Table2.*
FROM Table1 INNER JOIN Table2
ON Table1.invoiceID = Table2.invoiceID
WHERE Table1.CUSTOMERID = "463"
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
Having 5 tables
Table a_dates = id,
Table b_types = id, a_date_id, c_type_id,
Table c_types = id, name,
Table d_profiles = id, name, profile_type
Table e_ps = id, a_date_id, d_profile_id
From a_dates Need to get b_types,...then from b_types needs c_types name,... Then compare c_types name with d_profiles name and get d_profiles id.... if equals then create a records in e_ps with a_date_id, d_profile_id.
Could any one please help me in getting the query from inner join.
I tried like, it is incomplete query
INSERT INTO e_ps(id,a_date_id,a_date_type,d_profile_id,c_id)
SELECT '',a.id,'A',dp.id,'67' FROM d_profiles dp
INNER JOIN a_dates a ON {HERE I NEED NAME MATCHING WITH c_types name} = dp.name and dp.profile_type = 'A'
INNER JOIN a_dates ON a.id = a_dates.id
LEFT OUTER JOIN e_ps eps ON eps.a_date_type = 'A' AND eps.a_date_id = a_dates.id
WHERE eps.a_date_id IS NULL
This seems to be a relatively simple JOIN:-
INSERT INTO e_ps(id, a_date_id, d_profile_id)
SELECT NULL, a_dates.id, d_profiles.id
FROM a_dates
INNER JOIN b_types ON a_dates.id = b_types.a_date_id
INNER JOIN c_types ON b.c_type_id = c.id
INNER JOIN d_profiles ON c_types.name = d_profiles.name
With joins there are several types, and I suspect you are getting confused. Briefly:-
With an INNER JOIN it looks for a match that is on BOTH tables. If no
match the no record is returned.
With a LEFT OUTER JOIN it takes a record from the table on the left
and looks for a match on the table on the right. If a match great,
but if not then it still brings a row back but the columns from the
table on the right just have values of NULL.
A RIGHT OUTER JOIN is very much the same, just with the tables
reversed (most people including me avoid using this as it has no
advantages most of the time but just makes things confusing).
With a FULL OUTER JOIN it gets the records from both side, whether
they match or not. If they match then the columns from both are
returned, if not matched then the columns from one are returned. Not
that MySQL does not support a FULL OUTER JOIN (although there are
ways to emulate it).
A CROSS JOIN joins every combination of 2 tables. These are used when
there is no common column to match on but you want all combinations.
For example if you wanted a table of all employees and all days of
the week for each employee you would cross join a table of days of
the week against a table of employees (then for useful data you might
LEFT OUTER JOIN a table of holidays to the result).
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 am using the 3 following tables:
First table
id
response
Second table
responseid
patientid
Third table
patientid
The relationship between first and second table is on id and responceid.
The relationship between third and second is on patientid.
Now I need to retrieve values from these tables like all values from first and third tables with the help of matching with patientid from second and 3rd table.
How can I do this?
Basically if all of the columns that defines their relationship are not nullable, then INNER JOIN will suffice. But if they are nullable and you still want to display all records from firstTB, you need to use LEFT JOIN instead of INNER JOIN.
SELECT a.*, b.*, c.*
FROM firstTB a
INNER JOIN secondTB b
ON a.ID = b.responceID
INNER JOIN thirdTB c
ON b.patientID = c.patientID
To further gain more knowledge about joins, kindly visit the link below:
Visual Representation of SQL Joins
You're probably looking for INNER JOIN or JOIN in general:
SELECT
response.id,
response.responce,
patient.patientid
FROM
`response_table` as `response`
INNER JOIN
`relation_table` as `relation`
ON
relation.responceid = response.id
INNER JOIN
`patient_table` as `patient`
ON
relation.patientid = patient.patientid
try
SELECT first.*
, third.*
FROM first
INNER JOIN second ON ( second.responseid = first.id )
INNER JOIN third ON ( third.patientid = second.patientid )
;
honestly, and no insult intended, if you have difficulties in coming up with queries like this one on your own, consider some training on db basics and db development, the sooner the better (just hoping i haven't blundered myself ... ;-)).