I have a table like this
itemid | propertyname | propertyvalue
___________|______________|_______________
1 | point | 12
1 | age | 10
2 | point | 15
2 | age | 11
3 | point | 9
3 | age | 10
4 | point | 13
4 | age | 11
I need a query to select all items where age greater than 10 and point less than 12.
I tried
`select itemid from table where (propertyname="point" and propertyvalue < 12)
and (propertyname="age" and propertyvalue >10)`
It gives no results. How can I make it work?
you can use an inner join
SELECT
a.itemid
FROM
yourTable a
INNER JOIN
yourTable b
ON
a.itemid=b.itemid
AND a.propertyname='point'
AND b.propertyname='age'
WHERE
a.propertyvalue<12
AND b.propertyvalue>10
ok so in table a youre lookin for all items with the name point and a value smaller 12 and in table b youre looking for all items with the name age and a value greater 10. Then you only have to look for items, which are in both tables. For this you connect the two tables over the itemid. To connect tables you use the join. Hope this will help you to understand. If not ask again :)
To join a table to itself in the same query you can include the table twice in the FROM clause, giving it a different alias each time. Then you simply proceed with building your query as if you were dealing with two separate tables that just happen to contain exactly the same data.
In the query below the table example is aliased as a and b:
SELECT a.itemid
FROM example a, example b
WHERE a.itemid = b.itemid
AND a.propertyname = 'point'
AND a.propertyvalue < 12
AND b.propertyname = 'age'
AND b.propertyname > 10
Try It:
SELECT itemid FROM test_table WHERE propertyname="point" AND propertyvalue < 12 AND itemid IN(SELECT itemid FROM test_table WHERE propertyname="age" AND propertyvalue >10)
http://sqlfiddle.com/#!9/4eafc6/1
PLs Try this
select itemid from table where (propertyname="point" and propertyvalue < 12)
or (propertyname="age" and propertyvalue >10);
Here's one idea...
SELECT item_id
, MAX(CASE WHEN propertyname = 'point' THEN propertyvalue END point
, MAX(CASE WHEN propertyname = 'age' THEN propertyvalue END age
FROM a_table
GROUP
BY item_id
HAVING age+0 > 10
AND point+0 < 12;
You can use an inner join. Meaning, it's like you're going to work with 2 tables: the first one you're going to select the name="age" and val>10, and the second one is where you're going to select name="point" and val<12.
It's like you're creating an instance of your table that doesn't really exist. It's just going to help you extract the data you need at the same time.
Related
i have a table like this on a mysql database:
id | item
-----------
1 | 2
2 | 2
3 | 4
4 | 5
5 | 8
6 | 8
7 | 8
i want the result to be 3 record with the highest Item value
select max(item) returns only 1 value
how can i select multiple max values?
thank you
You can use a derived table to get the maximum value and join it back to the original table to see all rows corresponding to it.
select t.id, t.item
from tablename t
join (select max(item) as mxitem from tablename) x
on x.mxitem = t.item
Edit:
select t.co_travelers_id, t.booking_id, t.accounts_id
from a_co_travelers t
join (select accounts_id, max(booking_id) as mxitem
from a_co_travelers
group by accounts_id) x
on x.mxitem = t.booking_id and t.accounts_id = x.accounts_id
If you use an 'aggregate function' without GROUP BY only one row will be returned.
You may use GROUP BY , with aggregate functions.
Here is SQLFiddle Demo
SELECT id,max(item) AS item
FROM table_name
GROUP BY id
ORDER BY item DESC
LIMIT 3
Hope this helps.
There is the graphical explanation.
There is script mysql (low abstraction level, no inner join or sth)
select * from ocena, uczen where ocena.ocena = (SELECT MAX(ocena.ocena) FROM ocena WHERE ocena.przedmiot_id="4" and ocena.uczen_id="1") and ocena.uczen_id=uczen.id and ocena.przedmiot_id="4" and uczen_id="1"
The solution to the topic is evading me.
I have a table looking like (beyond other fields that have nothing to do with my question):
NAME,CARDNUMBER,MEMBERTYPE
Now, I want a view that shows rows where the cardnumber AND membertype is identical. Both of these fields are integers. Name is VARCHAR. Name is not unique, and duplicate cardnumber, membertype should show for the same name, as well.
I.e. if the following was the table:
JOHN | 324 | 2
PETER | 642 | 1
MARK | 324 | 2
DIANNA | 753 | 2
SPIDERMAN | 642 | 1
JAMIE FOXX | 235 | 6
I would want:
JOHN | 324 | 2
MARK | 324 | 2
PETER | 642 | 1
SPIDERMAN | 642 | 1
this could just be sorted by cardnumber to make it useful to humans.
What's the most efficient way of doing this?
What's the most efficient way of doing this?
I believe a JOIN will be more efficient than EXISTS
SELECT t1.* FROM myTable t1
JOIN (
SELECT cardnumber, membertype
FROM myTable
GROUP BY cardnumber, membertype
HAVING COUNT(*) > 1
) t2 ON t1.cardnumber = t2.cardnumber AND t1.membertype = t2.membertype
Query plan: http://www.sqlfiddle.com/#!2/0abe3/1
You can use exists for this:
select *
from yourtable y
where exists (
select 1
from yourtable y2
where y.name <> y2.name
and y.cardnumber = y2.cardnumber
and y.membertype = y2.membertype)
SQL Fiddle Demo
Since you mentioned names can be duplicated, and that a duplicate name still means is a different person and should show up in the result set, we need to use a GROUP BY HAVING COUNT(*) > 1 in order to truly detect dupes. Then join this back to the main table to get your full result list.
Also since from your comments, it sounds like you are wrapping this into a view, you'll need to separate out the subquery.
CREATE VIEW DUP_CARDS
AS
SELECT CARDNUMBER, MEMBERTYPE
FROM mytable t2
GROUP BY CARDNUMBER, MEMBERTYPE
HAVING COUNT(*) > 1
CREATE VIEW DUP_ROWS
AS
SELECT t1.*
FROM mytable AS t1
INNER JOIN DUP_CARDS AS DUP
ON (T1.CARDNUMBER = DUP.CARDNUMBER AND T1.MEMBERTYPE = DUP.MEMBERTYPE )
SQL Fiddle Example
If you just need to know the valuepairs of the 3 fields that are not unique then you could simply do:
SELECT concat(NAME, "|", CARDNUMBER, "|", MEMBERTYPE) AS myIdentifier,
COUNT(*) AS count
FROM myTable
GROUP BY myIdentifier
HAVING count > 1
This will give you all the different pairs of NAME, CARDNUMBER and MEMBERTYPE that are used more than once with a count (how many times they are duplicated). This doesnt give you back the entries, you would have to do that in a second step.
Not sure if this is possible but I have a schema like this:
id | user_id | thread_id
1 | 1 | 1
2 | 4 | 1
3 | 1 | 2
4 | 3 | 2
I am trying to retrieve the thread_id where user_id = 1 and 4. I know that in(1,4) does not fit my needs as its pretty much a OR and will pull up record 3 as well and Exists only returns a bool.
You may use JOIN (that answer already exists) or HAVING, like this:
SELECT
thread_id,
COUNT(1) AS user_count
FROM
t
WHERE
user_id IN (1,4)
GROUP BY
thread_id
HAVING
user_count=2
-check the demo. HAVING will fit better in case of many id's (because with JOIN you'll need to join as many times as many id you have). This is a bit tricky, however: you may do = comparison only if your records are unique per (user_id, thread_id); for example, your user_id can repeat, then use >=, like in this demo.
Try this with join, i guess you need to do AND operation with user_id must be 4 and 1 then
SELECT
t1.thread_id
FROM
TABLE t1
JOIN TABLE t2
ON (t1.user_id = t2.user_id)
WHERE t1.user_id = 1
AND t2.user_id = 4
UPDATED
id | id_list
1 | 2,3,5,7
2 | 1,4,5,6
3 | 1,4,6,7
4 | 2,3,5,8
5 | 1,2,4,8
6 | 2,3,7,8
7 | 1,3,6,9
8 | 4,5,6,9
9 | 7,8
let's say I'm up to the content of id=1
I wanted to select all the rows where id is in id_list of id=1 PLUS the row where id=1
so the result would be
rows with id = 1,2,3,5,7
How to do this query guys?
You can also use a self join
Using IN()
select * from atable a
join atable b on (a.id = b.id )
where 1 IN (a.id_list) or b.id =1
Fiddle with IN()
Using FIND_IN_SET()
select * from atable a
join atable b on (a.id = b.id )
where FIND_IN_SET('1', a.id_list) or b.id =1
Fiddle with FIND_IN_SET()
Using UNION ALL
select * from atable
where id =1
UNION ALL
select * from atable
where 1 IN (id_list)
Fiddle with UNION ALL
Your database design is broken; id_list should be represented as a join table instead of as a string. However, to solve your immediate problem:
select * from table where id=1
or id_list like '1%'
or id_list like '%,1,%'
or id_list like '%,1'
Adjust as needed for PreparedStatement. You have to provide all three cases because if you just did
or id_list like '%1%'
and id_list contained the value 11, you'd get an incorrect match
Try this (see SQL-Fiddle):
SELECT * FROM tbl
WHERE id = 1
OR INSTR((SELECT id_list FROM tbl WHERE id = '1'), id) > 0;
Tested with MySQL 5.5.30
try this one
select *
from tbl
where id=1
or id_list like '%1%'
This appears to call for a union of two sets. The one set would be the single row whose id matches the specified value:
SELECT
id
FROM
atable
WHERE
id = #id
The other set would be the result of this self-join:
SELECT
item.id
FROM
atable AS item
INNER JOIN
atable AS list
ON
FIND_IN_SET(item.id, list.id_list)
WHERE
list.id = #id
That is, the row with the specified id is matched against every row in the table on the condition that the other row's id is found in the specified row's id_list.
You can try the complete query at SQL Fiddle.
Please note that lists aren't a very good design feature. In your situation, it might be better to use a many-to-many table as suggested by #Othman. Only I would probably use a slightly different query to get the desired output, because his doesn't include the specified row itself:
SELECT
id
FROM
manytomany
WHERE
id = #id
UNION
SELECT
linked_id
FROM
manytomany
WHERE
id = #id
;
While the entries in manytomany are assumed to be unique, the query uses the UNION DISTINCT operator because of the potential duplicates returned by the first subquery, although it is possible to move the application of DISTINCT to the first subquery only like this:
SELECT DISTINCT
id
FROM
manytomany
WHERE
id = #id
UNION ALL
SELECT
linked_id
FROM
manytomany
WHERE
id = #id
;
That first subquery could actually be rewritten simply as SELECT #id AS id, but the rewrite would only make sense if the passed value was guaranteed to be valid, i.e. that it would definitely be found in manytomany.id.
Here's a demo for the other approach too (all three variations, including the SELECT #id AS id one).
I don't have an answer for your question but I encourage you to redesign your table like this I think this called many to many relation
id | friend
1 | 2
1 | 3
1 | 5
1 | 7
2 | 1
2 | 4
2 | 5
2 | 6
3 | 1
3 | 4
3 | 6
3 | 7
And then your query will be like this
SELECT DISTINCT(friend) FROM `new` WHERE id = 1
I am assuming you are using php..
My suggestion is to grab the id_list for id 1.
Explode that id_list on the comma, and then do another mysql query to grab the remaining results for 5|3|6|8
ex) $idarray = explode(",", $result);
select * from your_table where id in ('5','3','6','8')
OPTION 2:
SELECT * FROM your_table
WHERE id = '1'
OR id IN ('\''+(SELECT REPLACE(id_list,',','\',\'') FROM your_table WHERE id = '1')+'\'')
EDIT: Oops, sorry, that should be an OR instead.
Good day,
I have a MySQL table which has some duplicate rows that have to be removed while adding a value from one column in the duplicated rows to the original.
The problem was caused when another column had the wrong values and that is now fixed but it left the balances split among different rows which have to be added together. The newer rows that were added must then be removed.
In this example, the userid column determines if they are duplicates (or triplicates). userid 6 is duplicated and userid 3 is triplicated.
As an example for userid 3 it has to add up all balances from rows 3, 11 and 13 and has to put that total into row 3 and then remove rows 11 and 13. The balance columns of both of those have to be added together into the original, lower ID row and the newer, higher ID rows must be removed.
ID | balance | userid
---------------------
1 | 10 | 1
2 | 15 | 2
3 | 300 | 3
4 | 80 | 4
5 | 0 | 5
6 | 65 | 6
7 | 178 | 7
8 | 201 | 8
9 | 92 | 9
10 | 0 | 10
11 | 140 | 3
12 | 46 | 6
13 | 30 | 3
I hope that is clear enough and that I have provided enough info. Thanks =)
Two steps.
1. Update:
UPDATE
tableX AS t
JOIN
( SELECT userid
, MIN(id) AS min_id
, SUM(balance) AS sum_balance
FROM tableX
GROUP BY userid
) AS c
ON t.userid = c.userid
SET
t.balance = CASE WHEN t.id = c.min_id
THEN c.sum_balance
ELSE 0
END ;
2. Remove the extra rows:
DELETE t
FROM
tableX AS t
JOIN
( SELECT userid
, MIN(id) AS min_id
FROM tableX
GROUP BY userid
) AS c
ON t.userid = c.userid
AND t.id > c.min_id
WHERE
t.balance = 0 ;
Once you have this solved, it would be good to add a UNIQUE constraint on userid as it seems you want to be storing the balance for each user here. That will avoid any duplicates in the future. You could also remove the (useless?) id column.
SELECT SUM(balance)
FROM your_table
GROUP BY userid
Should work, but the comment saying fix the table is really the best approach.
You can create a table with the same structure and transfer the data to it with this query
insert into newPriceTable(id, userid, balance)
select u.id, p.userid, sum(balance) as summation
from price p
join (
select userid, min(id) as id from price group by userid
) u ON p.userid = u.userid
group by p.userid
Play around the query here: http://sqlfiddle.com/#!2/4bb58/2
Work is mainly done in MSSQL but you should be able to convert the syntax.
Using a GROUP BY UserID you can SUM() the Balance, join that back to your main table to update the balance across all the duplicates. Finally you can use RANK() to order your duplicate Userids and preserve only the earliest values.
I'd select all this into a new table and if it looks good, deprecate your old table and rename then new one.
http://sqlfiddle.com/#!3/068ee/2