I am trying to full join several queries, two will full join, the other won't. It gives error of
invalid use of on clause
Is there a comma or semicolon to be used when trying to full join queries?
select * from
(query1) query1
full join (query2) query2
on query1.x = query2.x; does not join thereafter
full join (query3) query3
on query1.x = query3.x;
Related
How to reduce the query execution time in mysql where table having records greater than 154381 and inner query should be used
This is my Query :
SELECT txn_gallery.gallery_image
FROM txn_gallery
WHERE villa_id IN(SELECT villa_id
FROM txn_notifications
LEFT JOIN mst_villa on mst_villa.sk_villa_id=txn_notifications.villa_id
WHERE txn_notifications.member_id='235' and txn_notifications.tran_status='Approved')
Your query is functionally identical to:
SELECT g.gallery_image
FROM txn_gallery g
JOIN txn_notifications n
ON n.villa_id = g.villa_id
WHERE n.member_id = 235
and n.tran_status = 'Approved'
An index on some combination of (villa_id,member_id,tran_status) would be useful
Its better to use join instead of inner query
JOIN can be faster than an equivalent subquery because the server might be able to optimize it better
So subqueries can be slower than LEFT [OUTER] JOIN
I have an 4 tables join query, when i execute without "where" takes like 13 seconds with where takes like 8 minutes.
I have no idea what to do in my mind when u use where to filter improve query perfomance but i'm mistaken
SELECT distinct tb_ProdutoComercial.nm_prodcomerc as tx_nome,
tb_parceiro.id_prodcomerc_pr as id_produto
FROM tb_vendedor
left join tb_tokenidparc
on tb_vendedor.nu_cdVendedorS4E = tb_tokenidparc.nu_cdVendedor4E_tk
left join tb_parceiro
on tb_tokenidparc.nu_cdCorretoraS4E_tk = tb_parceiro.id_corretora_pr
left join tb_ProdutoComercial
on tb_ProdutoComercial.id_prodcomerc = tb_parceiro.id_prodcomerc_pr
where tb_ProdutoComercial.en_status = '1'
EXPLAIN With Where
EXPLAIN Without Where
I'm looking for something with the same perfomance without where
As you are joining the tables on left side but you also filter them too that is the reason it is taking much time.
Here actually 5 queries are running according to the query.
Does this run better?
SELECT distinct tb_ProdutoComercial.nm_prodcomerc as tx_nome
,tb_parceiro.id_prodcomerc_pr as id_produto
FROM tb_vendedor
left join tb_tokenidparc on tb_vendedor.nu_cdVendedorS4E = tb_tokenidparc.nu_cdVendedor4E_tk
left join tb_parceiro on tb_tokenidparc.nu_cdCorretoraS4E_tk = tb_parceiro.id_corretora_pr
left join (select * from tb_ProdutoComercial where en_status='1') tb_ProdutoComercial on tb_ProdutoComercial.id_prodcomerc = tb_parceiro.id_prodcomerc_pr
I am getting this error call not unique table alias, Im not able to figure out the issue. I have a common date table connecting all. Also teacher table connecting two tables - Leave and Attendance. Please help
SELECT
trns_teacherattendance.Attendance_Status,
trns_teacherattendance.Attendance_Month,
trns_teacherattendance.AcademicYear_Id,
trns_teacherattendance.School_Id,
trns_teacherattendance.Bio_Code,
trns_teacherattendance.IsActive,
mst_holiday_teacher.Holiday_Name,
dates.dates,
leave_new_view_teacher.Leave_Status,
mst_teacher.Teacher_Name,
leave_new_view_teacher.LeaveDate
FROM
trns_teacherattendancemapping
LEFT OUTER JOIN
trns_teacherattendance
ON
(
trns_teacherattendancemapping.Bio_Code =
trns_teacherattendance.Bio_Code)
RIGHT OUTER JOIN
dates
ON
(
trns_teacherattendance.Attendance_Date = dates.dates)
LEFT OUTER JOIN
mst_teacher
ON
(
trns_teacherattendancemapping.Teacher_Id =
mst_teacher.Teacher_Id)
RIGHT OUTER JOIN
leave_new_view_teacher
ON
(
mst_teacher.Teacher_Id = leave_new_view_teacher.TID)
LEFT OUTER JOIN
leave_new_view_teacher
ON
(
dates.dates = leave_new_view_teacher.LeaveDate)
LEFT OUTER JOIN
mst_holiday_teacher
ON
(
dates.dates = mst_holiday_teacher.Holiday_Date) ;
You are joining twice to a table leave_new_view_teacher but you aren't giving it different aliases. Database can't know from which query/table you would like to reference your columns. Each join could pull different data/rows.
Assign aliases to these tables as a minimum requirement in this part:
RIGHT OUTER JOIN
leave_new_view_teacher AS lnvt1 -- here
ON
mst_teacher.Teacher_Id = leave_new_view_teacher.TID
LEFT OUTER JOIN
leave_new_view_teacher AS lnvt2 -- and here
ON
dates.dates = leave_new_view_teacher.LeaveDate
You will also need to properly classify columns in SELECT part:
SELECT
...
lnvt1.Leave_Status, -- you're probably getting this from first join
mst_teacher.Teacher_Name,
lnvt2.LeaveDate -- this probably comes from second join
You also don't need the parentheses for each ON clause, so I've removed them.
I have a query where I am using a full outer join. But in some instance,
it gives me a syntax error.
What could be the reason for this? I don't see any miscode in my query.
MySQL does not support full outer join, but you can simulate it as a union between a left and right join query:
SELECT * FROM pbsdev3.item t1
LEFT JOIN pbsdev3.item_ledger_entry t2 ON t1.No_ = t2.Item_No_
UNION ALL
SELECT * FROM pbsdev3.item t1
RIGHT JOIN pbsdev3.item_ledger_entry t2 ON t1.No_ = t2.Item_No_
WHERE t1.No_ IS NULL
Note that in general if you find yourself doing full outer joins often, it could imply that your keys and data model are not well defined. One reason why MySQL does not support full joins could be that you should not have to use it.
Full outer join is quite a pain in MySQL. The first thing I would note is that it should not be needed. The items should match in the two tables, so an inner join or left join should be sufficient:
SELECT i.*, ile.*
FROM pbsdev3.item i LEFT JOIN
pbsdev3.item_ledger_entry ile
ON i.No_ = ile.Item_No_;
If you really need full outer join, then gather together all the items and use left join:
select it.*, ile.*
from (select i.No_ from item i union
select ile.Item_No_ from item_ledger_entry ile
) i left join
item it
on it.No_ = i.No_ left join
item_ledger_entry ile
on ile.No = i.No;
My aim is to do exactly what a LEFT OUTER JOIN intends to do using the 4th venn diagram: SQL Diagrams:
My query isn't returning any values at all, where in fact, it should be returning all within the Consultant_Memberships minus the one that is stored within Consultant_Memberships_Lists.
Please see the SQL Fiddle for an easier understanding:
SELECT *
FROM consultant_memberships
LEFT OUTER JOIN consultant_memberships_list
ON consultant_memberships.`id` =
consultant_memberships_list.membership_id
WHERE consultant_memberships_list.consultant_id = $id
AND consultant_memberships_list.membership_id IS NULL
The query is using '5' as an ID for demonstration purposes to try and pick out the correct rows.
You current query is basically doing an INNER JOIN because of the consultant_id = 5 on the WHERE clause. I believe you actually want to use:
SELECT *
FROM consultant_memberships m
LEFT OUTER JOIN consultant_memberships_list l
ON m.`id` = l.membership_id
AND l.consultant_id = 5
WHERE l.membership_id IS NULL;
See SQL Fiddle with Demo
Use
SELECT *
FROM consultant_memberships
LEFT Outer JOIN consultant_memberships_list
ON consultant_memberships_list.membership_id = consultant_memberships.`id`
and consultant_memberships_list.consultant_id = 5
where consultant_memberships_list.membership_id IS NULL;
The Where clause used before in your query "consultant_memberships_list.consultant_id = 5 " was neglecting the left outer join.