I have the following table:
id | value | data | v
1 | val1 | dat1 | 1
2 | val1 | dat2 | 2
3 | val1 | dat3 | 3
4 | val2 | dat4 | 1
What I do is grab the data, each value, which has higher v.
No what I mean ..
Sql output I would like:
id | value | data | v
3 | val1 | dat3 | 3
4 | val2 | dat4 | 1
You need to identify the max value in a subquery and then join against the constant element
Fiddle
select *
from
Table1
join
(select max(v) MAXV, value from Table1 group by value) T
on T.MAXV = Table1.v and T.value=Table1.value
As gillyspy already commented, what you need is a subquery that returns the correct values. Check this code:
SELECT id, table1.value, data, v
FROM Table1
JOIN (SELECT MAX(v) MAXV, value
FROM Table1
GROUP BY value
) T ON T.MAXV = Table1.v
AND T.value = Table1.value;
Related
I have a table like this
+-------+-------+-------+-------+
| id | cid | grade |g_point|
+-------+-------+-------+-------+
| 1 | 10 | A+ | 1 |
| 2 | 10 | A+ | 1 |
| 3 | 10 | B | 3 |
| 4 | 11 | A | 2 |
| 5 | 11 | A+ | 1 |
| 6 | 12 | B | 3 |
the column g_point is the values associated to each grade. forexample A+ grade considers highest so I assign the value of A+ is one(highest starts from 1 to 10) and so on. These g_point values are constant. Now what I want to do is I want to show the maximum grade against each course and also if somehow there are only two entries of different grades I want to compare it with the g_point and choose whose value is lower because lower integer value means higher grade. the result should be like this and also sorted from top grade to lower.
+-------+-------+
| cid | grade |
+-------+-------+
| 10 | A+ |
| 11 | A+ |
| 12 | B |
I have tried this query
SELECT coursecodeID AS cid, (SELECT grade
FROM feedback
WHERE coursecodeID = cid
GROUP BY grade
ORDER BY COUNT(*) DESC LIMIT 0,1) AS g
FROM feedback
GROUP BY coursecodeID
but in this query I don't know how can I compare it with g_point value and also the courses is not showing in order(from highest grade to lowest).
NOTE: I want to choose the grade having the maximum number of occurrences per course id. For example here in this table course id 10 has 2 A+ grade so we'll consider A+ and if clash happens like one is A+ and the other is B+, then we'll have to compare it with the g_point
This works, but needs the 'g_point' to alse be returned.
SELECT cid,grade,MIN(g_point)
FROM grades
GROUP BY cid
This is more reliable, as it generates the Grade in the sub-query, and then appends it to the main table.
SELECT cid, (
SELECT grade
FROM grades g2
WHERE g2.cid = g1.cid
ORDER BY g_point
LIMIT 1
) AS grade
FROM grades g1
GROUP BY cid
You can use the following query:
SELECT DISTINCT m1.cid, m1.grade
FROM mytable AS m1
INNER JOIN (
SELECT cid, MIN(g_point) AS maxGrade
FROM mytable
GROUP BY cid ) m2
ON m1.cid = m2.cid AND m1.g_point = m2.maxGrade
The derived table contains the minimum g_point per cid. If you join it back to the original table, then you can get the maximum grade per cid.
Demo here
EDIT:
You can alternatively use a correlated sub-query:
SELECT cid, (SELECT grade
FROM mytable AS m2
WHERE m2.cid = m1.cid
ORDER BY g_point LIMIT 1) AS maxGrade
FROM mytable AS m1
GROUP BY cid
Demo here
EDIT2:
It looks like you want to get the grade having the maximum number of occurrences per cid. In case there are more than one grades sharing this maximum number, then fetch the grade with the lowest g_point.
You can do it using variables:
SELECT cid, grade
FROM (
SELECT cid, grade,
#row_number := IF (#cid <> cid,
IF (#cid := cid, 1, 1),
IF (#cid := cid, #row_number+1, #row_number+1)) AS rn
FROM (
SELECT cid, grade,
COUNT(*) AS cnt,
(SELECT g_point
FROM mytable AS m2
WHERE m1.grade = m2.grade
LIMIT 1) AS g_point
FROM mytable AS m1
GROUP BY cid, grade
) t
CROSS JOIN (SELECT #row_number:=-1, #cid:=-1) AS vars
ORDER BY cid, cnt DESC, g_point
) s
WHERE rn = 1
Demo here
Something to think about...
SELECT * FROM ints;
+---+
| i |
+---+
| 0 |
| 1 |
| 2 |
| 3 |
| 4 |
| 5 |
| 6 |
| 7 |
| 8 |
| 9 |
+---+
SELECT i
, CONCAT(CHAR((i/2)+64),IF(MOD(i,2)=1,'+',''))n
FROM ints
WHERE i > 0;
+---+------+
| i | n |
+---+------+
| 1 | A+ |
| 2 | A |
| 3 | B+ |
| 4 | B |
| 5 | C+ |
| 6 | C |
| 7 | D+ |
| 8 | D |
| 9 | E+ |
+---+------+
How to delete all rows from a mysql table if values of two columns are equal
Example Table
invoice_id| item_id | name | invoiced_qty | received_qty
---------------------------------------------------------
| 1 | 1 | item1 | 3 | 2
| 2 | 2 | item2 | 5 | 5
| 3 | 1 | item3 | 4 | 3
| 4 | 2 | item4 | 2 | 2
| 5 | 1 | item5 | 5 | 5
After deleting table needs to retains
invoice_id| item_id | name | invoiced_qty | received_qty
---------------------------------------------------------
| 1 | 1 | item1 | 3 | 2
| 3 | 1 | item3 | 4 | 3
The select query which i created is
SELECT * FROM table1 A
INNER JOIN table1 B ON A.item_id = B.item_id
AND A.invoice_id = B.invoice_id
AND A.invoiced_qty = B.received_qty
Thanks
Why not just SQL Fiddle:
DELETE FROM table1
WHERE invoiced_qty = received_qty
Your edit does not change anything. He is the SQL Fiddle demonstrating your SELECT query. According to your sample data A.invoice_id will never equal B.invoice_id. So you will not get any results.
Try this :
DELETE FROM table1 A
INNER JOIN table1 B ON A.item_id = B.item_id
WHERE A.invoiced_qty = B.received_qty
You could simply wrap your select statement and select values to be deleted by id, like this:
DELETE FROM table1
WHERE item_id IN (SELECT item_id FROM table1 A
INNER JOIN table1 B ON A.item_id = B.item_id
AND A.invoice_id = B.invoice_id
AND A.invoiced_qty = B.received_qty)
however you should accept answer by Linger as it is more straightforward solution, mine was to indicate that if you have something selected usually you can wrap and delete.
I have a table with an auto increment key id, item_no can be either one or two rows in a row (so they always have consecutive ids) that share the same ref but have different right/left (but technically item_no can be repeated multiple times throughout the table but that's not an issue), and description will sometimes be the same on the consecutive rows but sometimes different:
id | item_no | description | right\left | ref
1 | 1 | a1 | right | aaa
2 | 1 | a1 | left | aaa
3 | 2 | b1 | right | bbb
4 | 3 | c1 | right | ccc
5 | 3 | c2 | left | ccc
6 | 4 | d1 | right | ddd
7 | 4 | d1 | left | ddd
My issue is that I need item_no to append a -r or -l on to its value if the description of its 'matching' row is different.
So the result I am looking for is:
id | item_no | description | right\left | ref
1 | 1 | a1 | right | aaa
2 | 1 | a1 | left | aaa
3 | 2 | b1 | right | bbb
4 | 3-r | c1 | right | ccc
5 | 3-l | c2 | left | ccc
6 | 4 | d1 | right | ddd
7 | 4 | d1 | left | ddd
I am exporting the table to a csv but am not using much php, just a mysql statement and then looping out the results, is this possible within the mysql statement or will I have to rely on a php loop?
I would use this:
update
items inner join
(select item_no from items
group by item_no
having count(distinct description)>1) dup
on items.item_no=dup.item_no
set
items.item_no=concat(items.item_no, '-', substr(rightleft, 1,1))
If rows are always consecutive, you could also use this:
update
items i1 inner join items i2
on (i1.id=i2.id+1 or i1.id=i2.id-1)
and (i1.item_no=i2.item_no)
and (i1.description<>i2.description)
set i1.item_no=concat(i1.item_no, '-', substr(i1.rightleft, 1,1))
EDIT: if rows are always consecutive, and you just need a select and not an update, you could use this:
select
i1.id,
case when i1.description=i2.description or i2.id is null then i1.item_no else
concat(i1.item_no, '-', substr(i1.rightleft, 1,1)) end,
i1.description, i1.rightleft, i1.ref
from
items i1 left join items i2
on (i1.id=i2.id+1 or i1.id=i2.id-1) and (i1.item_no=i2.item_no)
order by i1.id
Try this:
SELECT
id,
CASE RightLeft
WHEN 'right' THEN CONCAT(item_no, '-r' )
WHEN 'left' THEN CONCAT(item_no, '-l' )
END AS item_no,
DESCRIPTION,
Rightleft,
ref
FROM Items
WHERE item_no IN
(
SELECT i1.item_no
FROM items i1
GROUP BY i1.item_no
HAVING(COUNT(DISTINCT description)) > 1);
SQL Fiddle Demo
This will give you:
| ID | ITEM_NO | DESCRIPTION | RIGHTLEFT | REF |
------------------------------------------------
| 4 | 3-r | c1 | right | ccc |
| 5 | 3-l | c2 | left | ccc |
I would rely on a PHP loop if you're using mysql, if you were using Oracle or SQL server then you could program a stored procedure.
You script should look something like this:
$dbh = new PDO('mysql:host='.DATABASE_HOST.';dbname='.DATABASE_NAME, DATABASE_USER, DATABASE_PASSWORD);
$dbh->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);
$data = $dbh->query("SELECT * FROM ExampleTable");
$dbh->beginTransaction();
foreach($data as $row)
{
$append = $row["right\left"] == "left" ? $row["item_no"]."-l" : $row["item_no"]."-r";
$stmnt = $dbh->prepare("UPDATE ExampleTable SET item_no = :item WHERE id = :id");
$stmnt->execute(array(":item" => $append,":id" => $row["id"]));
}
// Do some exception handling if something goes wrong you can allways do a rollback
// With PDO $dbh->rollBack();
$dbh->commit();
$dbh = null;
Something like this
UPDATE [dbo].[maTable] SET [item_no] = [item_no]+'r' WHERE not distinct [description] from [dbo].[maTable]
Should add an 'r' in the registration line where [description] is not identical (coded for SQL Server)
I need to filter only these table rows which have same values in x and y columns.
_______________________________________
|
| x | y | name |
________________________________________
|
| 1 | 2 | A |
|______________________________________
| 2 | 1 | B |
|______________________________________
| 1 | 2 | C |
|_______________________________________
The final result should be that I have A and C result. I need to filter these rows which has identical x and y values.
_______________________________________
|
| x | y | name |
________________________________________
|
| 1 | 2 | A |
|______________________________________
______________________________________
| 1 | 2 | C |
|_______________________________________
I' ve tried this code but I only managed to with one field.
select *
from auto
where x in (
select x
from auto
group by x
having count(*) > 1
);
SELECT t1.*
FROM tablename t1, tablename t2
WHERE t1.x = t2.x
AND t1.y = t2.y
AND t1.primary_key != t2.primary_key
select * from
auto a, ( SELECT x, y, COUNT(*) FROM auto GROUP BY x, y HAVING COUNT(*) > 1 ) b
where a.x = b.x
and a.y = b.y
will mark your other question as duplicate
I have a table where I save all row-changes that have ever occurred. The problem is that in the beginning of the application there was a bug that made a bunch of copies of every row.
The table looks something like this:
copies
|ID |CID |DATA
| 1 | 1 | DA
| 2 | 2 | DO
| 2 | 3 | DO (copy of CID 2)
| 1 | 4 | DA (copy of CID 1)
| 2 | 5 | DA
| 1 | 6 | DA (copy of CID 1)
| 2 | 7 | DO
CID is UNIQUE in table copies.
What I want is to remove all the duplicates of DATA GROUP BY ID that is after one another sorted by CID.
As you can see in the table, CID 2 and 3 are the same and they are after one another. I would want to remove CID 3. The same with CID 4 and CID 6; they have no ID 1 between them and are copies of CID 1.
After duplicates removal, I would like the table to look like this:
copies
|ID |CID |DATA
| 1 | 1 | DA
| 2 | 2 | DO
| 2 | 5 | DA
| 2 | 7 | DO
Any suggestions? :)
I think my question was badly asked because the answer everybody seems to think is the best gives this result:
ID | DATA | DATA | DATA | DATA | DATA | DATA | CID |
|Expected | Quassnoi |
1809 | 1 | 0 | 1 | 0 | 0 | NULL | 252227 | 252227 |
1809 | 1 | 0 | 1 | 1 | 0 | NULL | 381530 | 381530 |
1809 | 1 | 0 | 1 | 0 | 0 | NULL | 438158 | (missing) |
1809 | 1 | 0 | 1 | 0 | 1535 | 20090113 | 581418 | 581418 |
1809 | 1 | 1 | 1 | 0 | 1535 | 20090113 | 581421 | 581421 |
CID 252227 AND CID 438158 are duplicates but because CID 381530 comes between them; I want to keep this one. It's only duplicates that are directly after one another when ordering by CID and ID.
DELETE c.*
FROM copies c
JOIN (
SELECT id, data, MIN(copies) AS minc
FROM copies
GROUP BY
id, data
) q
ON c.id = q.id
AND c.data = q.data
AND c.cid <> q.minc
Update:
DELETE c.*
FROM (
SELECT cid
FROM (
SELECT cid,
COALESCE(data1 = #data1 AND data2 = #data2, FALSE) AS dup,
#data1 := data1,
#data2 := data2
FROM (
SELECT #data1 := NULL,
#data2 := NULL
) vars, copies ci
ORDER BY
id, cid
) qi
WHERE dup
) q
JOIN copies c
ON c.cid = q.cid
This solution empoys MySQL session variables.
There is a pure ANSI solution that would use NOT EXISTS, however, it would be slow due to the way MySQL optimizer works (it won't use range access method in a correlated subquery).
See this article in my blog for performance details for quite a close task:
MySQL: difference between sets
You can use a count in a subquery for this:
delete from copies
where
(select count(*) from copies s where s.id = copies.id
and s.data = copies.data
and s.cid > copies.cid) > 0
// EDITED for #Jonathan Leffler comment
//$sql = "SELECT ID,CID,DATA FROM copies ORDER BY CID, ID";
$sql = "SELECT ID,CID,DATA FROM copies ORDER BY ID, CID";
$result = mysql_query($sql, $link);
$data = "";
$id = "";
while ($row = mysql_fetch_row($result)){
if (($row[0]!=$id) && ($row[2]!=$data) && ($id!="")){
$sql2 = "DELETE FROM copies WHERE CID=".$row[1];
$res = mysql_query($sql2, $link);
}
$id=$row[0];
$data=$row[2];
}
delete from copies c where c.cid in (select max(cid) as max_cid, count(*) as num from copies where num > 1 group by id, data)