I am trying to join two tables and get the count and grouped by specific field. However, it outputs same count values even if the other table consist only two rows. How should I fix this?
Here's my code:
SELECT tbl1.preferredDay, COUNT(tbl1.preferredDay) as count_1, COUNT(tbl2.preferredDay) as count_2
FROM tblschedule as tbl1
LEFT JOIN tblappointments as tbl2 ON (tbl1.preferredDay = tbl2.preferredDay)
WHERE tbl1.preferredDay = tbl2.preferredDay
GROUP BY preferredDay;
Here is the output but it should be [15, 0][3, 3]
Your query is based on left join it will return the same count().
This is a working query for Mysql 8:
with tbl1 as (
SELECT preferredDay, count(1) as count_1
FROM tblschedule
GROUP BY preferredDay
),
tbl2 as (
SELECT preferredDay, count(1) as count_2
FROM tblappointments
GROUP BY preferredDay
)
select t1.preferredDay, t1.count_1, t2.count_2
from tbl1 t1
inner join tbl2 t2 on t1.preferredDay = t2.preferredDay
There are two WITHs to get separately the count and then an INNER JOIN to join those results
For Mysql 5.7 and lower :
select t1.preferredDay, t1.count_1, t2.count_2
from (
SELECT preferredDay, count(1) as count_1
FROM tblschedule
GROUP BY preferredDay
) as t1
inner join (
SELECT preferredDay, count(1) as count_2
FROM tblappointments
GROUP BY preferredDay
) as t2 on t1.preferredDay = t2.preferredDay
Related
Say I have a query which looks something like this:
select step0.a, step1.a, step2.a
from (select id from tbl1) as step
inner join tbl1 as step0 on step0.id = step.id
left join tbl1 as step1 on step1.b = step0.a
left join tbl1 as step2 on step2.b = step1.a
This works fine. Now, say I want to union these results with the reverse of a and b, i.e.:
select * from (
(
select step0.a, step1.a, step2.a
from (select id from tbl1) as step
inner join tbl1 as step0 on step0.id = step.id
left join tbl1 as step1 on step1.b = step0.a
left join tbl1 as step2 on step2.b = step1.a
)
union (
select step0.b, step1.b, step2.b
from (select id from tbl1) as step
inner join tbl1 as step0 on step0.id = step.id
left join tbl1 as step1 on step1.a = step0.b
left join tbl1 as step2 on step2.a = step1.b
)
) rows
This also works fine. But notice that the select id from tbl1 subquery is duplicated.
The question I have, is how do I store the results of this subquery, without using temporary tables, such that each select in the union can reference it?
select *
from
(
SELECT id, imei1, status
FROM `owarranty_imei` mto
WHERE EXISTS
(
SELECT 1
FROM `owarranty_imei` mti
WHERE mto.imei1=mti.imei1
LIMIT 1, 1
)
) t1
left join `owarranty_warranty_activations` as t2 on t1.id=t2.imei_id
where t2.id is null
limit 100
this is my query. In owarranty_imei has more than 100000 records. i want to get duplicates from imei table which owarranty_imei not in owarranty_warranty_activation table. This query work for few records but when i run it for more than 1000000 records its not working
SELECT
mto.id,
mto.imei1,
mto.status
FROM
`owarranty_imei` mto
INNER JOIN
`owarranty_imei` mti ON mto.imei1=mti.imei1
LEFT JOIN
`owarranty_warranty_activations` as t2 ON mto.id=t2.imei_id
GROUP BY mto.id
HAVING COUNT(t2.id)=0
I have one query that returns count and some columns from two tables and another query that returns count and a column from two tables.
I want to combine this two queries that results in single row per id.
i have tried this:
select
(select a.column_1 as ID,a.column_2,COUNT(b.column_2) as Cnt1
from
table_1 a left outer join table_2 b on a.ID=b.ID
group by
a.column_1 as ID,a.column_2
)
where EXISTS
(select a.column_1 as ID,COUNT(c.column_2) as Cnt2
from
table_1 a left outer join table_3 c on a.ID=c.ID
group by
a.column_1
)
without knowing your real schema...based on your sample query, assuming your inner queries are correct (some minor syntax error). You might want to do something like this.
select *
FROM
(select a.column_1 as ID,a.column_2,COUNT(b.column_2) as Cnt1
from table_1 a left outer join table_2 b on a.ID=b.ID
group by a.column_1,a.column_2
) T1
INNER JOIN
(select a.column_1 as ID,COUNT(c.column_2) as Cnt2
from table_1 a left outer join table_3 c on a.ID=c.ID
group by a.column_1
) T2 ON T1.ID = T2.ID
sqlfiddle
You might want to replace select * with select T1.ID,T1.column_2,Cnt1,Cnt2 based on your comment.
Table column headers: n,t1,t2
entries :
1 A B
2 A C
3 B C
4 D E
5 B A
How do I count total number of rows each letter appears in t1 MINUS the number of rows they appear in t2 ? I need to do something like following 2 lines in 1 query :
select count(*) as val,t1 from table group by t1
select count(*) as val,t2 from table group by t2
Thanks,
Martin
Here is one way:
select t1, max(t1cnt) - max(t2cnt) as diff
from ((select t1, count(*) as t1cnt, 0 as t2cnt
from t
group by t1
) union all
(select t2, 0 as t1cnt, count(*) as t2cnt
from t
group by t2
)
) t
group by t1
Using the union all ensures that you get all possible values from both columns, even values that only appear in one column.
You can use the following query to get the result. This query first gets a list of all the distinct t1 and t2 values (this is the UNION query). Once you have the list of these values, then you can use a LEFT JOIN to the original queries that you posted:
select d.col, coalesce(totT1, 0) - coalesce(totT2, 0) Total
from
(
select t1 col
from entries
union
select t2 col
from entries
) d
left join
(
select count(*) totT1, t1
from entries
group by t1
) d1
on d.col = d1.t1
left join
(
select count(*) totT2, t2
from entries
group by t2
) d2
on d.col = d2.t2;
See SQL Fiddle with Demo
I am joining 2 tables -tbl1 and tbl2. Left join give all data from tbl1 which is in tbl2 or only on tbl1. Right join gives data from tbl2 which is don't exists in tbl1.
I want to combine both results.
What is the best way to do this so that I get all data from tbl1 and tbl2?
The only you can do that is by using UNION. MySQL doesn't support FULL JOINjust like in MSSQL.
SELECT *
FROM tbl1 t1
LEFT JOIN tbl2 t2
ON t1.col = t2.col
UNION
SELECT *
FROM tbl1 t1
RIGHT JOIN tbl2 t2
ON t1.col>= t2.<col
SEE HERE: Simulating FULL JOIN in MYSQL
By the way, UNION has optional keyword ALL,when the ALL is omitted, UNION automatically selects DISTINCT rows from the resultset.
EXAMLE:
SELECT *
FROM tableA
UNION ALL
SELECT *
FROM tableA
this can result duplicates rows
ColA ColB
==================
1 John
2 Jade
2 Jade
3 Hello
BUT if you omit the word ALL
SELECT *
FROM tableA
UNION
SELECT *
FROM tableA
this can result distinct rows only
ColA ColB
==================
1 John
2 Jade
3 Hello
What you want is FULL JOIN
LEFT JOIN + RIGHT JOIN = FULL JOIN
So try this:
SELECT * FROM tbl1
LEFT JOIN tbl2 ON tbl1.id = tbl2.id
UNION
SELECT * FROM tbl1
RIGHT JOIN tbl2 ON tbl1.id = tbl2.id
The UNION clause combines the results of two SQL queries into a single table of all matching rows.
Here's an alternative that can be easily extended if you have a full join of more than 2 tables:
SELECT t1*, t2.*
FROM
( SELECT col
FROM tbl1
UNION
SELECT col
FROM tbl2
) AS d
LEFT JOIN tbl1 AS t1
ON t1.col = d.col
LEFT JOIN tbl2 AS t2
ON t2.col = d.col ;
you have to use FULL OUTER JOIN, But mysql doesnt support it.. You could do this for getting the result:
SELECT *
FROM tbl1 t1 LEFT JOIN tbl2 t2
ON t1.<col> = t2.<col>
UNION
SELECT *
FROM tbl1 t1 RIGHT JOIN tbl2 t2
ON t1.<col>= t2.<col>