What I'm trying to do is update all rows column with the same id with increasing number and when there is no more of this id I to go on the next one.
Table:
id column
1 0
1 0
2 0
2 0
3 0
3 0
I tried:
SELECT #i:=0;
UPDATE table SET column = #i:=#i+1
This way I updated the column but the column values goes like 1 2 3 4 5 6 and
I must reset the #i back to 0 everytime when id of the row has changed.
OR:
Table:
id column
1 1
1 2
2 1
2 2
3 1
3 2
I guess this should be made by a loop. But can't get it. Plus when I tried to make a loop in the MySQL (PHPMyAdmin), it gave me an error. What I read around is that I can't make loops directly in the PHPMyAdmin or I misunderstood it?
UPDATE table ,(SELECT #curRow := 0, #curCol := '') r SET column=
( CASE id WHEN #curCol THEN #curRow := #curRow + 1 ELSE #curRow := 1 AND #curCol := id END)
Test
Related
I have sample Data Set
ID Name Active
1 Mii 0
1 Mii 1
2 Rii 0
2 Rii 1
3 Lii 0
4 Kii 0
4 Kii 1
5 Sii 0
How I can get active records along with Inactive records for other ID's.
ID Name Active
1 Mii 1
2 Rii 1
3 Lii 0
4 Kii 1
5 Sii 0
I have taken all the data into 2 temp tables because lot of joins are there
select * from tmp1 where active = 1
UNION ALL
select * from tmp2 where active = 0 AND
NOT EXISTS (SELECT 1 FROM tmp1 WHERE Active = 1 )
can anyone tell me is there any better way to write in MYSQL
Assuming that active can only be 0 or 1, aggregation could help:
SELECT id,
name,
max(active) active
FROM elbat
GROUP BY id,
name;
max(active) is 1, if there is a record with the id and name that has a 1 in active, as 1 > 0. Otherwise it is 0, the only value.
Using analytical functions:
select * from (
SELECT ID, NAME, RANK() OVER ( ORDER BY ACTIVE desc) AS RN
FROM TABLE1) a where rn = 1;
I have a table with data that has an indicator as a number, it is not an ID or foreign key. This number is repeated several times in the table.
I need to print all the rows with included incremental row number within the same indicator value, so 1 is there 2 times, 2 is there 3 times, 3 is there 1 time.
Desired output:
name | indicator | rownumber
a 1 1
b 1 2
c 2 1
d 2 2
e 2 3
f 3 1
I have found this solution to count the rows but I do not know how to reset the counter if the indicator is changed.
The query I have so far is but this is incrementally counting the rows
SELECT name, indicator,
#rownum := #rownum + 1 as row_number
FROM rownumtable
CROSS JOIN (SELECT #rownum := 0) r
ORDER BY name ASC
BUT it prints the row number - see it on SQL Fiddle
name | indicator | row_number
a 1 1
b 1 2
c 2 3
d 2 4
e 2 5
f 3 6
Is there a way how to reset the row_number counter for specific group of same values in the MySQL query?
SELECT name, indicator,
#rownum := case when #prevIndicator <> indicator then 1 else #rownum + 1 end as rownumber,
#prevIndicator := indicator
FROM rownumtable
CROSS JOIN (SELECT #rownum := 0, #prevIndicator := 0) r
ORDER BY name ASC
SQLFiddle demo
How would I get the row number of a mysql output, for example:
select * from table
name age
David 12
Frank 13
I want to get the row number, like so:
select *, row_num from table
row name age
1 David 12
2 Frank 13
The row number on the left -- 1 through 7 -- not a part of the data itself.
In mysql, you have to use User-Defined Variables.
SELECT #rowno := #rowno + 1 AS row_no, *
FROM table
CROSS JOIN (SELECT #rowno := 0) t
-- ORDER BY age
I currently have a query that counts the 'parent_id' value for each row and adds it within each row.
For example, if I have 4 records that have the has the value '1432' under 'parent_id' it will show the count value 4 under the 'count' column.
I am trying to limit the amount of rows based on the count number.
For example, let's say we want to exceed the number of records per 'parent_id' to 2. if the 'parent_id' has reached the third record, it just passes on and it won't return that record.
Example of existing table:
ID parent_id count(parent_id)
1 1234 2
2 1234 2
3 3221 3
4 3221 3
5 3221 3
6 5432 1
7 4312 1
The result I'd like to get is:
ID parent_id count(parent_id)
1 1234 2
2 1234 2
3 3221 2
4 3221 2
5 5432 1
6 4312 1
This is a select per group query:
SELECT id, parent_id, rn
FROM (
SELECT #rn:=CASE WHEN #parent_id=parent_id
THEN #rn+1
ELSE 1
END AS rn
, #parent_id:=parent_id AS parent_id
, id
FROM t, (SELECT #rn:=0,#parent_id:='') AS u
ORDER BY parent_id,id
) as s
WHERE rn <= 2
FIDDLE
Mihai's answer may work, but it is not guaranteed to work. The problem is that MySQL does not guarantee the order of evaluation of expressions in the select. And, there are even occasions where it does not evaluate them in the expected order.
So, when using variables, it is safest to put all assignments in a single expression:
SELECT id, parent_id, rn
FROM (SELECT (#rn := if(#parent_id = parent_id, #rn + 1,
if(#parent_id := parent_id, 1, 1)
)
) as rn,
t.*
FROM t CROSS JOIN
(SELECT #rn := 0, #parent_id := '') params
ORDER BY parent_id, id
) t
WHERE rn <= 2;
I would like data rows numbered upon selecting from a table. Problem is that, I need not sequential numbering, but it should be numbered from 1 to 3 and so to the end, like below:
1 | first row
2 | second row
3 | third row
1 | fourth row
2 | and
3 | ....
1
2
3
I'm trying this query, but it does not work correctly:
mysql -> SET #n = 0;
-> SELECT
CASE
WHEN nnn = 3 THEN #n := 0
ELSE nnn
END
FROM (
SELECT #n := #n + 1 AS nnn FROM mytable
) AS t;
How to make it working correctly?
Adapted from this answer: With MySQL, how can I generate a column containing the record index in a table?
SELECT MOD(#curRow := #curRow + 1, 3) AS row_number
FROM mytable m
JOIN (SELECT #curRow := 0) r;
If you only need to select and assuming that there is column, say "id", that is sequential, then following query should help:
SELECT IF ((id%3) = 0, 3 , (id%3)) AS new_id, <other columns> FROM <table_name>;
Hope it helps...