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PORemove duplicates the simplest way / explanation
 

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    <p>First I would like to remark that I (as a Newb) did search through several Q &amp; A regarding duplicates in a table though unfortunately for me, I couldn't manipulate the code being used as answer.</p> <p>My table is made out of a report being sorted in SQL Server 2008.</p> <p>I would like to know how do I remove duplicate records and with an explanation.</p> <pre><code>"MyTable": Column1 (PK-auto incremental table's record ID) Column2 (some TXT) Column3 (Some TXT) Column4 (SmallDateTime) Column5 is empty </code></pre> <p>Column5 will hold the value of <code>SUM(count of deleted duplicates including this survived row)</code></p> <p>The key to the solution in may case is if <code>[column2 and column3]</code> have multiple records with same content (hence Duplicates) only they don't always share the same date (<code>column4</code>).</p> <p>From this:</p> <pre><code>col1 col2 col3 col4 col5 ---- ----- ---- ----------- ---- 1 [abc] [4] [10/1/2012] null 2 [abc] [1] [12/1/2012] null 3 [ghi] [6] [4/1/2012] null 4 [def] [5] [8/1/2012] null 5 [abc] [4] [10/1/2012] null 6 [def] [5] [12/1/2012] null 7 [ghi] [6] [15/1/2012] null 8 [abc] [4] [17/1/2012] null 9 [ghi] [6] [6/1/2012] null 10 [abc] [1] [13/1/2012] null </code></pre> <p>Into this:</p> <pre><code>col1 col2 col3 col4 col5 ---- ----- ---- ----------- ---- 8 [abc] [4] [17/1/2012] 2 10 [abc] [1] [13/1/2012] 3 6 [def] [5] [12/1/2012] 2 7 [ghi] [6] [15/1/2012] 3 </code></pre> <p>Meaning leave the latest (1) as a representation of every duplicated record.</p> <p>++ReEditing++</p> <p>Aaron Bertrand shawnt00 e2nburner... and rest of u all i can't say how much i thank your Reply although i did not yet comprehend that mass of code. i am now going to check those codes but not b4 thanking you guys !!</p> <p>when i first started to program and needed sql querys, after using </p> <pre><code>Select * From MyTable </code></pre> <p>... my 1'st SQL Statement ...</p> <p>i said HEY i know SQL !!! .... Now ... look at that deep knowledge of you guys ... THANKS A LOT i know that this post in StackOverFlow will be further useful for other beginners too</p>
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    1. COSee GROUP BY, MAX and SUM.
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    2. CO@pst Actually, `COUNT` too in his case
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    3. COthanks but it is too complicated for me as i usually do is learn from tutorials , in this case i really need a solution wich will be a c# code behind , that (i guess...) triggers a stored proc...
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