Saturday, 17 October 2015

CTE , ROW_NUMBER() PARTITION BY , useful tools when face with duplicate data

I recently came across an issue where I was retrieving data for a UI and dealing with potential dupes. for my purposes I used CTEs and row_number function to solve my particular issue.

 A CTE is essentially a kind of temporary table or a named result set off of a physical table (sort of like an in-line view).








With this function, you can number rows in your result set.  Even better, you can PARTITION BY to split your result set up into groups.  I might not want to see 1-10 as my row numbers, I might want to see 1-5 and 1-5 based on some column that I decide to partition the data by.  Note, this is a horizontal partition of rows.




 

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