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POt-sql most efficient row to column? crosstab for xml path, pivot
 

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    <p>I am looking for the most performant way to turn rows into columns. I have a requirement to output the contents of the db (not actual schema below, but concept is similar) in both fixed width and delimited formats. The below FOR XML PATH query gives me the result I want, but when dealing with anything other than small amounts of data, can take awhile.</p> <pre><code> select orderid ,REPLACE(( SELECT ' ' + CAST(ProductId as varchar) FROM _details d WHERE d.OrderId = o.OrderId ORDER BY d.OrderId,d.DetailId FOR XML PATH('') ),'&amp;#x20;','') as Products from _orders o </code></pre> <p>I've looked at pivot but most of the examples I have found are aggregating information. I just want to combine the child rows and tack them onto the parent.</p> <p>I should also point out I don't need to deal with the column names either since the output of the child rows will either be a fixed width string or a delimited string.</p> <p>For example, given the following tables:</p> <pre><code>OrderId CustomerId ----------- ----------- 1 1 2 2 3 3 DetailId OrderId ProductId ----------- ----------- ----------- 1 1 100 2 1 158 3 1 234 4 2 125 5 3 101 6 3 105 7 3 212 8 3 250 </code></pre> <p>for an order I need to output:</p> <pre><code>orderid Products ----------- ----------------------- 1 100 158 234 2 125 3 101 105 212 250 </code></pre> <p>or</p> <pre><code>orderid Products ----------- ----------------------- 1 100|158|234 2 125 3 101|105|212|250 </code></pre> <p>Thoughts or suggestions? I am using SQL Server 2k5.</p> <p>Example Setup: </p> <pre><code> create table _orders ( OrderId int identity(1,1) primary key nonclustered ,CustomerId int ) create table _details ( DetailId int identity(1,1) primary key nonclustered ,OrderId int ,ProductId int ) insert into _orders (CustomerId) select 1 union select 2 union select 3 insert into _details (OrderId,ProductId) select 1,100 union select 1,158 union select 1,234 union select 2,125 union select 3,105 union select 3,101 union select 3,212 union select 3,250 CREATE CLUSTERED INDEX IX_CL__orders on _orders(OrderId) CREATE NONCLUSTERED INDEX IX_NCL__orders on _orders(OrderId) INCLUDE (CustomerId) CREATE CLUSTERED INDEX IX_CL_details on _details(OrderId) CREATE NONCLUSTERED INDEX IX_NCL_details on _details(OrderId) INCLUDE (DetailId,ProductId) </code></pre> <p>using FOR XML PATH:</p> <pre><code> select orderid ,REPLACE(( SELECT ' ' + CAST(ProductId as varchar) FROM _details d WHERE d.OrderId = o.OrderId ORDER BY d.OrderId,d.DetailId FOR XML PATH('') ),'&amp;#x20;','') as Products from _orders o </code></pre> <p>which outputs what I want, however is very slow for large amounts of data. One of the child tables is over 2 million rows, pushing the processing time out to ~ 4 hours.</p> <pre><code>orderid Products ----------- ----------------------- 1 100 158 234 2 125 3 101 105 212 250 </code></pre>
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