I've two tables like this:
First :
id
num
1
a
2
b
3
c
Second:
id
first_id
value
11
1
a1
12
1
a2
13
1
a3
And I need to get result like this:
id
value
1
a1-a2-a3
I've tried with query:
SELECT first.id, (SELECT second.value FROM second
WHERE second.first_id = first.id) AS value
FROM first
But I've got #1242 error. How I can do it?
You can use group_concat()
select first_id as id,
group_concat(`value` order by `value` separator '-') as combined_values
FROM second_table
group by first_id
Related
I have a table having three columns:
A B C
1 2 2
2 2 2
3 1 1
4 1 2
I want the count of those values which have C equal to 2 but with distinct values of B
So in this case for C = 2, count = 2 (B=2 and B=1)
I used the following command:
Select count(*) from mytable where C=2 group by (B)
but it yields:
count(*)
3
I have tried using "distinct" but it can't be use to select from one column
Have you tried
SELECT COUNT(DISTINCT B) FROM mytable WHERE C = 2;
Use sub query like this:
Select count(*) from (
select distinct B where c=2
)
I have the following [table a]
id result
1 a
1 b
1 b
1 c
2 e
2 e
2 e
2 f
I'm getting the following after doing a group_concat
select id , Group_Concat(result) from [table a]
group by id
id result
1 a,b,b,c
2 e,e,e,f
BUT i want to display the no of times a value occurs before the value in the result set to avoid redundancy like the following
id result
1 a,2 b,c
2 3 e,f
How can I achieve it ?
Group by ID and result first to get the count. Then group by ID to build your strings.
select
id,
group_concat(case when cnt = 1 then result else concat(cnt, ' ', result) end) as results
from
(
select id, result, count(*)
from mytable
group by id, result
) t
group by id;
I have a table with 100 000 record, I want to select only the none repeated.
In another word, if the row are duplicated did not show it at all
ID Name Reslut
1 Adam 10
2 Mark 10
3 Mark 10
result
ID Name Reslut
1 Adam 10
any ideas ?
You could join a query on the table with a query that groups by the name only returns the unique names:
SELECT *
FROM mytable t
JOIN (SELECT name
FROM mytable
GROUP BY name
HAVING COUNT(*) = 1) s ON t.name = s.name
Using the same set :
ID Name Result
1 Adam 10
2 Mark 10
3 Mark 10
4 Mark 20
I'm guessing the final solution would be:
ID Name Result
1 Adam 10
4 Mark 20
Using the above query previously suggested I modified it to take the result into consideration:
SELECT t1.*
FROM myTable t1
JOIN
(
SELECT name, result
FROM myTable
GROUP BY name, result
HAVING COUNT(*) = 1
) t2
WHERE
t1.name=t2.name and
t1.result = t2.result;
My current table looks like this:
ID TYPE QUANTITY
1 A1 3
2 B1 2
3 A1 2
4 B1 8
And after doing the query I want to get that:
ID TYPE QUANTITY SUM
1 A1 3 5
2 B1 2 10
3 A1 2 5
4 B1 8 10
The SUM column consist of summed quantities of items with the same type.
My approach is to use a derived table which aggregates the quantity by type first and then join this result with the original data:
select
t.id,
t.type,
t.quantity,
tmp.overall
from
table t join (
select
table.type,
sum(table.quantity) as overall
from
table
group by
table.type
) tmp on t.type = tmp.type
SELECT t.ID,t.TYPE,t.QUANTITY,x.SUM FROM TABLE t LEFT JOIN
(SELECT ID,TYPE,QUANTITY,SUM(QUANTITY) AS SUM FROM TABLE GROUP BY TYPE)x
ON t.type=x.type
SQL Fiddle
I haven't tried the query but see what happens if you do this:
SELECT
ID,
myTable.TYPE,
QUANTITY,
aaa.summy
FROM myTable
JOIN
(
SELECT
TYPE,
SUM(QUANTITY) summy
FROM myTable
GROUP BY TYPE
) aaa
ON aaa.TYPE = myTable.TYPE
Hi there m trying to calculate the row count for same value,
id,value
1 | a
2 | b
3 | c
4 | d
5 | e
and my query is
select value, count(*) as Count from mytable where id in('4','2','4','1','4') group by value having count(*) > 1
for which my expected output will be,
value,Count
d | 3
b | 1
a | 1
Thanks, any help will be appreciated
Try that:
SELECT value, count(value) AS Count
FROM mytable m
WHERE value = m.value
GROUP BY value
SELECT t.id, t.value, COUNT(t.id)
FROM
test t
JOIN
( SELECT 1 AS id
UNION ALL SELECT 3
UNION ALL SELECT 3
UNION ALL SELECT 4
UNION ALL SELECT 1
UNION ALL SELECT 1 ) AS tmp
ON t.id = tmp.id
GROUP BY t.id
Sample on sqlfiddle.com
See also: Force MySQL to return duplicates from WHERE IN clause without using JOIN/UNION?
Of course, your IN parameter will be dynamic, and thus you will have to generate the corresponding SQL statement for the tmp table.
That's the SQL-only way to do it. Another possibility is to have the query like you have it in your question and afterwards programmatically associate the rows to the count passed to the IN parameter.