David Lean (9/21/2010)

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Nice article & Nice solution. But I would caution anyone about to blindly using this in production. It is only the 1st part of the process.

Problem 1: need to Fix Declarative Referential Integrity (DRI) for the rows deleted.
Invariably the duplicate rows you are about to remove will be referenced by the foreign keys in another table. When you delete these rows you must keep a copy of the Keys of the rows you deleted & map them to the key of the “duplicate” row you kept. That way you have some lookup table you can use to correct all the foreign key references.

If a foreign key referenced only one of the rows you are deleting, isn't that by definition not a duplicate? So then in that case can't you just delete with the unique key?

prakashp 84206 (6/1/2012)

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Hi,
The output of my query contains duplicate records (i.e. column1 value is similar but other column's value different) as well as single record having column2 value blanks(-). now I want to select only one record out of duplicate records for which column2 values are present (eliminating records for which column2 is blanks(-) from duplicate records) and all other single records having column2 values blanks.

My query's Present Output
column1 column2 column3
abc xyz pqr
abc - klm
ijk - uvw
plo - ujn
yhk ttg wea
yhk - erf

Expected Output
column1 column2 column3
abc xyz pqr
ijk - uvw
plo - ujn
yhk ttg wea

Can someone help me. Thanks in advance.