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Adding a UNIQUE CONSTRAINT to an existing column with duplicate values

GSunMay 23 2013 — edited May 23 2013

Hello Oracle Forums, I have a table that contains 11,901 rows. I tried to define the UNIQUE constraint on the xcode column but received an error: the column already contain duplicate values! I issued following SQL 'SELECT COUNT(*) FROM states;' the result is 11,901 and 'SELECT COUNT(DISTINCT (xcode)) FROM states;' the result is 11,680. Hence to enforce this unique key I must remove the 221 rows. Please how can I achieve this?

This post has been answered by jeneesh on May 23 2013

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