On 19 July 2010 15:01, Richard Quadling <[email protected]> wrote:
> On 19 July 2010 05:44, Peter <[email protected]> wrote:
>> Hi All,
>>
>> I have a table which contain's some duplicate rows. I just want to delete
>> the duplicate records alone
>> not original records.
>>
>> Assume my table as look as below
>>
>> column1 column2
>> 1
>> a
>> 1
>> a
>> 2
>> b
>> 3
>> c
>> 3
>> c
>>
>>
>>
>> i want the above table need to be as below, After executing the mysql
>> query.
>>
>> column1
>> column2
>> 1
>> a
>> 2
>> b
>> 3
>> c
>>
>>
>>
>>
>> Thanks in advance..
>>
Slightly more concise ...
-- Delete everything except the UniqueIDs we want to keep.
DELETE FROM
Table
WHERE
UniqueID NOT IN
(
-- Get the earliest UniqueIDs for each Col1, Col2 pairing.
SELECT
MIN(UniqueID)
FROM
Table
GROUP BY
Col1,
Col2
)
http://www.devx.com/tips/Tip/14665
DELETE
Table
FROM
Table T1,
Table T2
WHERE
T1.Col1 = T2.Col1
AND
T1.Col2 = T2.Col2
AND
T1.UniqueID > T2.UniqueID
http://www.cryer.co.uk/brian/sql/sql_delete_duplicates.htm
etc.
Many different ways.
http://www.orafaq.com/faq/how_does_one_eliminate_duplicates_rows_from_a_table
Method 3 should be the fastest.
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