Suppose I have a table t1 like
mysql> select * from t1;
+------+-------+------+
| id | level | gap |
+------+-------+------+
| 1 | 6 | 50 |
| 1 | 5 | 10 |
| 2 | 5 | 12 |
| 2 | 5 | 10 |
| 3 | 8 | 4 |
| 3 | 9 | 1 |
| 3 | 9 | 3 |
| 3 | 7 | 2 |
+------+-------+------+
I want to insert a row (3,6,7) into here.I mean it is below in first 5 row.
Is it possible in mysql?
Just do
INSERT INTO t1 (id, level,gap) VALUES (3,6,7)
Records in a table do not have a prescribed order. The order has to be defined during a SELECT by supplying a suitable ORDER BY clause.
So, if you want the new record to be listed in 5th position use ORDER BY id, level.
Related
I have a MySQL table like this:
+------+--------+--------+
| ID | UserID | Score |
+------+--------+--------+
| 1 | 3 | 12 |
| 2 | 3 | 11 |
| 3 | 3 | 12 |
| 4 | 2 | 14 |
| 5 | 4 | 8 |
| 6 | 2 | 13 |
+------+--------+--------+
From this I want to top 3 scores from entire table and a top score from particular user
+------+--------+--------+
| ID | UserID | Score |
+------+--------+--------+
| 4 | 2 | 14 |
| 6 | 2 | 13 |
| 3 | 3 | 12 |
| 5 | 4 | 8 |
+------+--------+--------+
Is this something I can get done in a single query?
Any help is appreciated
Thanks in advance!
spoiler alert ;)
(SELECT * FROM tableA ORDER BY score DESC LIMIT 3)
UNION
(SELECT * FROM tableB WHERE UserID = 4 ORDER BY score DESC LIMIT 1);
For certain definitions of "single query", sure... If you're willing to use sub queries or a union.
The best performance will probably come from two queries, but you can join them in a UNION for convenience if you wish.
I have a table like this:
// numbers
+----+--------+
| id | numb |
+----+--------+
| 1 | zero |
| 2 | one |
| 3 | two |
| 4 | three |
| 5 | four |
| 6 | five |
| 7 | six |
| 8 | seven |
| 9 | eight |
| 0 | nine |
+----+--------+
Now I'm trying to copy/paste the value of each row (just numb column) to the upper column. So this is expected result:
+----+--------+
| id | numb |
+----+--------+
| 1 | one |
| 2 | two |
| 3 | three |
| 4 | four |
| 5 | five |
| 6 | six |
| 7 | seven |
| 8 | eight |
| 9 | nine |
| 0 | zero |
+----+--------+
Actually I can do that by PHP. I mean I can fetch all rows and shift one itam and then update them. But I want to know can I do that by pure mysql?
All the rows except the max of id will get updated. The max id will still have the same numb. (in this case 9,'eight')
update tablename t1
JOIN tablename t2 on t1.id = t2.id-1
set t1.numb = t2.numb;
Sample Fiddle
Maybe something like
How do I UPDATE from a SELECT in SQL Server?
and use the id+1 for table2.
i am loosing it over the following problem:
i have a table with participants and points. each participant can have up to 11 point entries of which i only want the sum of the top 6.
in this example lets say we want the top 2 of 3
+----+---------------+--------+
| id | participantid | points |
+----+---------------+--------+
| 1 | 1 | 11 |
+----+---------------+--------+
| 2 | 3 | 1 |
+----+---------------+--------+
| 3 | 3 | 4 |
+----+---------------+--------+
| 4 | 2 | 3 |
+----+---------------+--------+
| 5 | 1 | 5 |
+----+---------------+--------+
| 6 | 2 | 10 |
+----+---------------+--------+
| 7 | 2 | 9 |
+----+---------------+--------+
| 8 | 1 | 3 |
+----+---------------+--------+
| 9 | 3 | 4 |
+----+---------------+--------+
as a result i want something like
+---------------+--------+
| participantid | points |
+---------------+--------+
| 2 | 19 |
+---------------+--------+
| 1 | 16 |
+---------------+--------+
| 3 | 8 |
+---------------+--------+
(it should be ordered DESC by the resulting points)
is this at all possible with mysql? in one query?
oh and the resulting participant ids should be resolved into the real names from another 'partcipant' table where
+----+------+
| id | name |
+----+------+
| 1 | what |
+----+------+
| 2 | ev |
+----+------+
| 3 | er |
+----+------+
but that should be doable with a join at some point... i know...
Using one of the answers from ROW_NUMBER() in MySQL for row counts, and then modifying to get the top.
SELECT ParticipantId, SUM(Points)
FROM
(
SELECT a.participantid, a.points, a.id, count(*) as row_number
FROM scores a
JOIN scores b ON a.participantid = b.participantid AND cast(concat(a.points,'.', a.id) as decimal) <= cast(concat(b.points,'.', b.id) as decimal)
GROUP BY a.participantid, a.points, a.id
) C
WHERE row_number IN (1,2)
GROUP BY ParticipantId
Had an issue with ties until I arbitrarily broke them with the id
I have two tables containing fields as below.
Table 1
| SetID | InQty | Day |
| 1 | 10 | 1 |
| 2 | 10 | 2 |
| 3 | 10 | 3 |
Table 2
| SetID | OtQty | Day |
| 1 | 1 | 5 |
| 1 | 2 | 6 |
| 1 | 3 | 7 |
SetID in table 2 is linked with SetId in table 1. Day is placed in place of date, just for convenience only. Expected Output,
| Day | InQty | OtQty |
| 1 | 10 | |
| 5 | | 1 |
| 6 | | 2 |
| 7 | | 3 |
Blank Space can be filled with NULL or Zero.
It appears you are querying ONLY for set ID = 1 otherwise, I would expect to see in/out values for Set 2 and 3. You should be able to get with a simple UNION
select t1.Day, t1.InQty, 0 OutQty
from Table1 t1
where SetID = 1
order by t1.Day
union select t2.Day, 0, t2.OtQty
from Table2 t2
where SetID = 1
Now, if you want totals spanning different "setID"s and keeping them differentiated from each other, just add the setID as a column and also add to the group by clause as well.
I've got tbl_items in my user database that I want to sort user rankings on a particular item with certain id (514). I have test data on my dev environment with this set of data:
mysql> select * from tbl_items where classid=514;
+---------+---------+----------+
| ownerId | classId | quantity |
+---------+---------+----------+
| 1 | 514 | 3 |
| 2 | 514 | 5 |
| 3 | 514 | 11 |
| 4 | 514 | 46 |
| 5 | 514 | 57 |
| 6 | 514 | 6 |
| 7 | 514 | 3 |
| 8 | 514 | 27 |
| 10 | 514 | 2 |
| 11 | 514 | 73 |
| 12 | 514 | 18 |
| 13 | 514 | 31 |
+---------+---------+----------+
12 rows in set (0.00 sec)
so far so good :) I wrote the following query:
set #row=0;
select a.*, #row:=#row+1 as rank
from (select a.ownerid,a.quantity from tbl_items a
where a.classid=514) a order by quantity desc;
+---------+----------+------+
| ownerid | quantity | rank |
+---------+----------+------+
| 11 | 73 | 1 |
| 5 | 57 | 2 |
| 4 | 46 | 3 |
| 13 | 31 | 4 |
| 8 | 27 | 5 |
| 12 | 18 | 6 |
| 3 | 11 | 7 |
| 6 | 6 | 8 |
| 2 | 5 | 9 |
| 7 | 3 | 10 |
| 1 | 3 | 11 |
| 10 | 2 | 12 |
+---------+----------+------+
12 rows in set (0.00 sec)
that ranks correctly the users. However in a table with lots of records, I need to do the following:
1) be able to get small portion of the list, around where the user ranking actually resides, something that would get me the surrounding records, preserving the overall rank:
I tried to do these things with setting a user variable to the ranking of the current user and by using offset and limit, but couldn't preserve the overall ranking.
This should get me something like the following (for instance ownerId=2 and surroundings limit 5:
+---------+----------+------+
| ownerid | quantity | rank |
+---------+----------+------+
| 3 | 11 | 7 |
| 6 | 6 | 8 |
| 2 | 5 | 9 | --> ownerId=2
| 7 | 3 | 10 |
| 1 | 3 | 11 |
+---------+----------+------+
5 rows in set (0.00 sec)
2) I'd also need another query (preferably single query) that gets me the top 3 places + the ranking of particular user with certain id, preferably with a single query, no matter if he's among the top 3 places or not. I couldn't get this as well
It would look like the following (for instance ownerId=2 again):
+---------+----------+------+
| ownerid | quantity | rank |
+---------+----------+------+
| 11 | 73 | 1 |
| 5 | 57 | 2 |
| 4 | 46 | 3 |
| 2 | 5 | 9 | --> ownerId=2
+---------+----------+------+
4 rows in set (0.00 sec)
Also I'm in a bit of a concern about the performance of the queries on a table with millions of records...
Hope someone helps :)
1) 5 entries around a given id.
set #row=0;
set #rk2=-1;
set #id=2;
select b.* from (
select a.*, #row:=#row+1 as rank, if(a.ownerid=#id, #rk2:=#row, -1) as rank2
from (
select a.ownerid,a.quantity
from tbl_items a
where a.classid=514) a
order by quantity desc) b
where b.rank > #rk2 - 3
limit 5;
Though you'll get an extra column rank2: you probably want to filter it out by explicit list of columns instead of b.*. Maybe it's possible whith a having clause rather than an extra nesting.
2) 3 top ranked entries + 1 specific id
select b.* from (
select a.*, #row:=#row+1 as rank
from (
select a.ownerid,a.quantity
from tbl_items a
where a.classid=514) a
order by quantity desc) b
where b.rank < 4 or b.ownerid=#id