How can I form the following statement in MySql, that it will work?
select a,b,c from xx where a in concat(select y from abc where x='a','%');
Notice: The subquery returns more than one line!
Example
|---A----|
|/backup/|
|/foto/ |
And the a in concat should return all items where the subquery is like the following example:
|/backup/23/x.txt |
|/backup/xx/asdf |
|/backup/x.txt |
That's the reason why I need the concat!
It is difficult to tell exactly what you are after here because your example data appears to contradict your question, but I think you need to use the EXISTS clause, rather than IN:
SELECT a, b, c
FROM xx
WHERE EXISTS
( SELECT 1
FROM abc
WHERE abc.x = 'a'
AND xx.a LIKE CONCAT(abc.y, '%')
);
Example on SQL Fiddle
Related
This looks like it should be really easy question, but I've been looking for an answer for the past two days and can't find it. Please help!
I have two tables along the lines of
texts.text_id, texts.other_stuff...
pairs.pair_id, pairs.textA, pairs.textB
The second table defines pairs of entries from the first table.
What I need is the reverse of an ordinary LEFT JOIN query like:
SELECT texts.text_id
FROM texts
LEFT JOIN text_pairs
ON texts.text_id = text_pairs.textA
WHERE text_pairs.textB = 123
ORDER BY texts.text_id
How do I get exclusively the texts that are not paired with A given textB? I've tried
WHERE text_pairs.textB != 123 OR WHERE text_pairs.textB IS NULL
However, this returns all the pairs where textB is not 123. So, in a situation like
textA TextB
1 3
1 4
2 4
if I ask for textB != 3, the query returns 1 and 2. I need something that will just give me 1.
The comparison on the second table goes in the ON clause. Then you add a condition to see if there is no match:
SELECT t.text_id
FROM texts t LEFT JOIN
text_pairs tp
ON t.text_id = tp.textA AND tp.textB = 123
WHERE tp.textB IS NULL
ORDER BY t.text_id ;
This logic is often expressed using NOT EXISTS or NOT IN:
select t.*
from texts t
where not exists (select 1
from text_pairs tp
where t.text_id = tp.textA AND tp.textB = 123
);
Good day all.
I'm facing a little problem with a mySql query. let's assume we have a table with a coulmn in which the values are pairs, but unified in the same field, so something like this:
id | serviceName
----+-------------
1 | foo - bar
2 | foo - doo
3 | foo - tep
4 | bee - bar
5 | bee - blo
I would like to select distinct the first part of serviceName, in this case foo, bee.
the desired output should be:
foo
bee
in the resultset.
what I've thought right now is something about making a SELECT DISTINCT a FROM REPLACE ( (SELECT serviceName as a FROM tableName), ' - ***', '')
but i'm not really sure if it is possible, and how to make it. I only would like to select the first part of the field, and I would like to take only distinct vlaues of it... it is possible? I need a right direction pointing,, I can make researches by my self.
thanks in advance.
Assuming that you always want to split on a dash -, this should work for you.
SELECT DISTINCT LEFT(serviceName, LOCATE('-', serviceName) - 2) FROM tableName;
SQLFiddle
IS this what you are looking at ?
select substring_index(serviceName,'-',1) as `first_part`
from test
group by `first_part`
DEMO
A MySQL query needs the results of a subquery in different places, like this:
SELECT COUNT(*),(SELECT hash FROM sets WHERE ID=1)
FROM sets
WHERE hash=(SELECT hash FROM sets WHERE ID=1)
and XD=2;
Is there a way to avoid the double execution of the subquery (SELECT hash FROM sets WHERE ID=1)?
The result of the subquery always returns an valid hash value.
It is important that the result of the main query also includes the HASH.
First I tried a JOIN like this:
SELECT COUNT(*), m.hash FROM sets s INNER JOIN sets AS m
WHERE s.hash=m.hash AND id=1 AND xd=2;
If XD=2 doesn't match a row, the result is:
+----------+------+
| count(*) | HASH |
+----------+------+
| 0 | NULL |
+----------+------+
Instead of something like (what I need):
+----------+------+
| count(*) | HASH |
+----------+------+
| 0 | 8115e|
+----------+------+
Any ideas? Please let me know! Thank you in advance for any help.
//Edit:
finally that query only has to count all the entries in an table which has the same hash value like the entry with ID=1 and where XD=2. If no rows matches that (this case happend if XD is set to an other number), so return 0 and simply hash value.
SELECT SUM(xd = 2), hash
FROM sets
WHERE id = 1
If id is a PRIMARY KEY (which I assume it is since your are using a single-record query against it), then you can just drop the SUM:
SELECT xd = 2 AS cnt, hash
FROM sets
WHERE id = 1
Update:
Sorry, got your task wrong.
Try this:
SELECT si.hash, COUNT(so.hash)
FROM sets si
LEFT JOIN
sets so
ON so.hash = si.hash
AND so.xd = 2
WHERE si.id = 1
I normally nest the statements like the following
SELECT Count(ResultA.Hash2) AS Hash2Count,
ResultA.Hash1
FROM (SELECT S.Hash AS Hash2,
(SELECT s2.hash
FROM sets AS s2
WHERE s2.ID = 1) AS Hash1
FROM sets AS S
WHERE S.XD = 2) AS ResultA
WHERE ResultA.Hash2 = ResultA.Hash1
GROUP BY ResultA.Hash1
(this one is hand typed and not tested but you should get the point)
Hash1 is your subquery, once its nested, you can reference it by its alias in the outer query. It makes the query a little larger but I don't see that as a biggy.
If I understand correctly what you are trying to get, query should look like this:
select count(case xd when 2 then 1 else null end case), hash from sets where id = 1 group by hash
I agree with the other answers, that the GROUP BY may be better, but to answer the question as posed, here's how to eliminate the repetition:
SELECT COUNT(*), h.hash
FROM sets, (SELECT hash FROM sets WHERE ID=1) h
WHERE sets.hash=h.hash
and sets.ID=1 and sets.XD=2;
Got this:
Table a
ID RelatedBs
1 NULL
2 NULL
Table b
AID ID
1 1
1 2
1 3
2 4
2 5
2 6
Need Table a to have a comma separated list as given in table b. And then table b will become obsolete:
Table a
ID RelatedBs
1 1,2,3
2 4,5,6
This does not rund through all records, but just ad one 'b' to 'table a'
UPDATE a, b
SET relatedbs = CONCAT(relatedbs,',',b.id)
WHERE a.id = b.aid
UPDATE: Thanks, 3 correct answers (marked oldest as answer)! GROUP_CONCAT is the one to use. No need to insert commas between the ids using relatedids = CONCAT(relatedids,',',next_id) that is done automatic by GROUP_CONCAT.
You'll have to use the mysql group_concat function in order to achieve this: http://dev.mysql.com/doc/refman/5.1/en/group-by-functions.html#function_group-concat
Look into GROUP_CONCAT(expr)
mysql> SELECT student_name,
-> GROUP_CONCAT(DISTINCT test_score
-> ORDER BY test_score DESC SEPARATOR " ")
-> FROM student
-> GROUP BY student_name;
You can't do that in standard SQL. You could write a stored procedure to do that. I had a similar problem, but I was using PostgreSQL so I was able to resolve it by writing a custom aggregate function so that you can do queries like
select aid, concat(id)
from b group by
aid
Update: MySQL has a group_concat aggregate function so you can do something like
SELECT id,GROUP_CONCAT(client_id) FROM services WHERE id = 3 GROUP BY id
as outlined here.
I've got a table, called for example, "node", from which I need to return values for as shown:
SELECT nid FROM node WHERE type = "book"
After I get a list of values let's say:
|**nid**|
|123|
|12451|
|562|
|536|
Then I need to take these values, and check another table, for rows where column 'path' has values as "node/123", "node/12451" (numbers the previous request returned) in one joined request. It all would be easier if collumn 'path' had simple numbers, without the 'node/'.
And then also count the number of identical i.e. 'node/123' returned.
End result would look like:
nid | path | count(path) | count(distinct path)
123 |node/123| 412 | 123
562 |node/562| 123 | 56
Works fine if done in multiple separated queries, but that won't do.
select a.nid from node a join othertable b
on b.path = concat("node/", a.nid) where type='book'
You can probably do something like the following (nid may require additional conversion to some string type):
SELECT *
FROM OtherTable
JOIN node ON path = CONCAT('node/', nid)
WHERE type = 'book'
Thank you all for your help. Basically, the problem was that I didn't know how to get nid and node/ together, but concat helped.
End result looks something like:
SELECT node.nid, accesslog.path, count(accesslog.hostname), count(distinct accesslog.hostname)
FROM `node`, `accesslog`
WHERE node.uid=1
AND node.type='raamat'
AND accesslog.path = CONCAT('node/', node.nid)
GROUP BY node.nid