Update first row of duplicate rows from sql table - sql

In sql table I select duplicate IDs which count is > 1 .Then I need to update only first row of selecting duplicate id rows.How to update just first row value.
Thanks in advance.

Assuming you have something like this:
SELECT ID
FROM ProductView
GROUP BY ID
HAVING COUNT(*) > 1
You will need to create a loop around the query and then select a result using TOP 1 and matching the ID. You can create the loop using a cursor.

Related

Access query finding the duplicates without using DISTINCT

i have this query
SELECT PersonalInfo.id, PersonalInfo.[k-commission], Abs(Not IsNull([PersonalInfo]![k-commission].[Value])) AS CommissionAbsent
FROM PersonalInfo;
and the PersonalInfo.k-commission is a multi value field. the CommissionAbsent shows duplicate values for each k-commission value. when i use DISTINCT i get an error saying that the keyword cannot be used with a multi value field.
now i want to remove the duplicates and show only one result for each. i tried using a WHERE but i dont know how.
edit: i have a lot more columnes and in the example i only showed the few i need.
You can use GROUP BY and COUNT to solve your problem, here is an example for it
SELECT clmn1, clmn2, COUNT(*) as count
FROM table
GROUP BY clmn1, clmn2
HAVING COUNT(*) > 1;
the query groups the rows in the table by the clmn1 and clmn2 columns, and counts the number of occurrences of each group. The HAVING clause is then used to filter the groups and only return the groups that have a count greater than 1, which indicates duplicates.
If you want to select all, then you can do like this
SELECT *
FROM table
WHERE (clmn1, clmn2) IN (SELECT clmn1, clmn2
FROM table
GROUP BY clmn1, clmn2
HAVING COUNT(*) > 1)
SELECT PersonalInfo.id, PersonalInfo.[k-commission], Abs(Not IsNull([PersonalInfo]![k-commission].[Value])) AS CommissionAbsent
FROM PersonalInfo
GROUP BY PersonalInfo.id, PersonalInfo.[k-commission], Abs(Not IsNull([PersonalInfo]![k-commission].[Value]))
HAVING COUNT(*) > 1

SQL delete rows with same value in column

I have column "name" with the same values.
For example:
select * table WHERE name Like 'Kate'
Result: 2 rows with this name.
I need leave only one row that has this name (random) in such rows.
And don't show other entries that have the same names.
How can I do this? Thanks.
you can use limit when you delete
DELETE FROM table WHERE name Like 'Kate' limit 1
delete from QQNAMES
where name like 'Kate%'
AND ID <> (select id from QQNAMES
where name like 'Kate%'
and ROWNum <=1);
Will delete all names in 'Kate%' pattern except the first one
Note: Not all database systems support the SELECT TOP clause. MySQL supports the LIMIT clause to select a limited number of records, while Oracle uses ROWNUM. from: w3schools
Try something like that;
delete from table where Id IN(
select Id from table WHERE name Like 'Kate' limit 1)

To Remove Duplicates from Netezza Table

I have a scenario for a type2 table where I have to remove duplicates on total row level.
Lets consider below example as the data in table.
A|B|C|D|E
100|12-01-2016|2|3|4
100|13-01-2016|3|4|5
100|14-01-2016|2|3|4
100|15-01-2016|5|6|7
100|16-01-2016|5|6|7
If you consider A as key column, you know that last 2 rows are duplicates.
Generally to find duplicates, we use group by function.
select A,C,D,E,count(1)
from table
group by A,C,D,E
having count(*)>1
for this output would be 100|2|3|4 as duplicate and also 100|5|6|7.
However, only 100|5|6|7 is only duplicate as per type 2 and not 100|2|3|4 because this value has come back in 3rd run and not soon after 1st load.
If I add date field into group by 100|5|6|7 will not be considered as duplicate, but in reality it is.
Trying to figure out duplicates as explained above.
Duplicates should only be 100|5|6|7 and not 100|2|3|4.
can someone please help out with SQL for the same.
Regards
Raghav
Use row_number analytical function to get rid of duplicates.
delete from
(
select a,b,c,d,e,row_number() over (partition by a,b,c,d,e) as rownumb
from table
) as a
where rownumb > 1
if you want to see all duplicated rows, you need join table with your group by query or filter table using group query as subquery.
wITH CTE AS (select a, B, C,D,E, count(*)
from TABLE
group by 1,2,3,4,5
having count(*)>1)
sELECT * FROM cte
WHERE B <> B + 1
Try this query and see if it works. In case you are getting any errors then let me know.
I am assuming that your column B is in the Date format if not then cast it to date
If you can see the duplicate then just replace select * to delete

Query for showing whole records where a particular field is entered twice

I have a problem here in that I don't know how to execute this S Q L query as I am not sure of the correct syntax...
I am trying to select all records from a record set (populated by a table), where a particular field is entered twice...
please what query should i use to get all records which showing double records in a field.
Try doing something like this:
SELECT "YourFieldName(s)", COUNT(*) AS RecordCount
FROM "YourTableName"
GROUP BY "YourFieldName(s)"
HAVING COUNT(*) > 1
"YourFieldName(s)" can be multiple columns if that is what you are checking duplicates on.
Select columnname,count(*) as cnt
from dbo.table
group by columnname
having count(*) > 1
this gives you the rows which has duplicates in the column " columnname" . edit to your requirement.

SQL Query MAX with SUm

I have a table where i have ID,matchid,point1,point2. I need to get the ID which has the maximum points but the problem i am facing is i need find max record depending on sum of both (point1+point), I have no idea how I can get the max with the combination of 2 columns i have tried query such as,
SELECT MAX(column1+column2) FROM table
MAX(SUM(column1,column2)) FROM table
but nothing works I am using Ms:Access
This will return more than one answer if more than one sum=max:
SELECT ID FROM Table1
WHERE ([Field1]+[Field2])=(
SELECT Max([Field1]+[Field2]) AS Expr1
FROM Table1)
You can use a subquery e.g.
select id from table where point1+point2 = (select max(point1+point2) from table)
Note that this will return multiple rows if more than one record has the same maximum points.