![]() We thank our dad dearly for his love, encouragement and life lessons. and Elizabeth (Costa) Willett, he had resided in Acushnet for many years. His gracious smile filled the room.īorn in New Bedford, a son of the late Richard A. Willett, 54, of Acushnet, died unexpectedly March 30, 2015, due to a fishing accident in Nantucket Sound. and Elizabeth (Costa) Willett, he resided in Acushnet for many years. Born in New Bedford, a son of the late Richard A. Willett, Stephen Michael age 55 of Edina, passed away unexpectedly on July 23, 2014. My heart and prayers go out to you Rita, and your family. After removing the duplicates, you can then remove the identity column.He loved the home building industry with a passion. Of course another possibility is to add an identity column so that you can use the first method of this post. You can also do it the other way around, first a SELECT INTO then drop the original table and then sp_rename on the new table (but you still miss a few things like the indexes). The disadvantage is that you don’t have any index/constraints/triggers/… on tablename anymore. The advantage of this second method is that you save one step. SELECT DISTINCT * INTO tablename FROM tablename_old Or rename the original table and select the distinct entries directly as the original table: sp_rename 'tablename', 'tablename_old' INSERT INTO tablename SELECT * FROM #mytemptable In this case, you have to create a new table containing only distinct entries and then…Įither copy it back in the original table after truncating it: SELECT DISTINCT * INTO #mytemptable FROM tablename If you have thousands or millions of duplicates, this is definitely not a good solution. Of course this is kind of a lot of manual work and you only want to do it for a few combinations. So you need to delete 4: SET ROWCOUNT 4ĭELETE FROM tablename WHERE xxx='xxx_value_1' AND yyy='yyy_value_1'Īnd you can repeat it for all values returned by the SELECT statement. So you know you have 5 rows with these two values for xxx and yyy. If you have few duplicate entries, you can use ROWCOUNT to make sure that for each set of duplicate rows you delete all of them except one.įirst you need to find out which sets of duplicate entries you have and how many entries you have in each set: SELECT xxx, yyy, COUNT(*) FROM tablename GROUP BY xxx, yyy HAVING COUNT(*) > 1 There are basically two methods to clean up the duplicates: If you do not have something like a row_id, it’s getting a little bit more difficult since you cannot directly reference a row. (t1.yyy=t2.yyy OR (t1.yyy is null AND t2.yyy is null)) If you also want to handle null values you need to replace: t1.xxx=t2.xxx AND t1.yyy=t2.yyyīy: (t1.xxx=t2.xxx OR (t1.xxx is null AND t2.xxx is null)) AND Note that I assume that we’re talking about non-null values. Xxx and yyy being the columns you want to use to identify duplicates. Here an example keeping the lowest row_id: DELETE FROM tablename t1 WHERE t1.row_id > (SELECT MIN(t2.row_id) FROM tablename t2 WHERE t1.xxx=t2.xxx AND t1.yyy=t2.yyy) In the first case, identifying the row to keep is quite easy: you need to get the minimum (or maximum) value of your key (let’s call it row_id from now on) and delete all rows with the same values for the other columns but a higher (or lower) row_id. some kind of row ID) and in the second one you can’t. The difference is just that in the first case you can reference each column with a key (i.e. In both cases, you need to delete all rows but one, with the same values for X columns. The duplicates are 100% identical rows.The duplicates are entries where the other columns of the rows are identical but the unique key is different. There is a unique key on this table (e.g.in order to copy the data to a table with a unique index or to add a unique index on this table), you can use one of the following methods.įirst it’s important to know what kind of duplication we’re talking about: If you need to delete duplicate records from a table (e.g.
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