title: TSQL: What am I doing wrong with my Partition By?
body: <pre><code>ItemID | NumberOfUses | LastMaint | Partition
   0111          1           NULL         1
  
   0111          1         1/1/2015       2
   0111          2         1/1/2015       2
   0111          3         1/1/2015       2
   0111          4         1/1/2015       2
   0111          5         1/1/2015       2
  
   0111          1         4/1/2015       3
   0111          2         4/1/2015       3
   0111          3         4/1/2015       3
  
   0111          1         7/1/2015       4
   0111          2         7/1/2015       4
   0111          3         7/1/2015       4
   0111          4         7/1/2015       4
   0111          5         7/1/2015       4
   0111          6         7/1/2015       4 
   0111          7         7/1/2015       4 
   0111          8         7/1/2015       4 
   0111          9         7/1/2015       4
  </code></pre>
  
  <p>What I am trying to figure out is how to get the Partition column to look like the above. (I added a space between the different groups/partitions just to make it easier to look at).</p>
  
  <p>I've been trying to do this using something close to the query below.  I've tried just about every combination of columns in the ROW_NUMBER() OVER() </p>
  
  <pre><code>SELECT [ItemID]
        ,[NumberOfUses]
        ,[LastMaintenance]
        ,ROW_NUMBER() OVER (PARTITION BY ?????????
                              ORDER BY ???????) [Partition]     
      FROM [ItemsHistory]
  
  ORDER BY [Partition]
  </code></pre>