By: Greg Robidoux | Updated: 2019-03-22 | Comments (68) | Query Optimization
In SQL Server 2000 there was not a simple way to create cross-tab queries, but a new option first introduced in SQL Server 2005 has made this a bit easier. We took a look at how to create cross-tab queries in SQL Server 2000 in this previous tip and in this tip we will look at the SQL Server PIVOT feature to allow you produce cross-tab results.
We will use the SQL Server PIVOT to create cross-tab results and show an example.
Let's say we have data in a table that looks like this:
And what we want to do is to rearrange the output to look like below. First you have the data rows such as SalesPerson, and then columns for each Product with the summarized SalesAmount value for each cross section.
Let's create a sample table and insert some data that we can use with a PIVOT query.
CREATE TABLE ProductSales ( SalesPerson varchar(20), Product varchar(20), SalesAmount money ) GO INSERT INTO ProductSales SELECT 'Bob','Pickles',100.00 UNION SELECT 'Sue','Oranges',50.00 UNION SELECT 'Bob','Pickles',25.00 UNION SELECT 'Bob','Oranges',300.00 UNION SELECT 'Sue','Oranges',500.00 GO
Here is a simple PIVOT query that allows us to pull the cross-tab results as shown above.
SELECT SalesPerson, [Oranges] AS Oranges, [Pickles] AS Pickles FROM ( SELECT SalesPerson, Product, SalesAmount FROM ProductSales ) ps PIVOT ( SUM (SalesAmount) FOR Product IN ( [Oranges], [Pickles]) ) AS pvt
So how does this work?
There are three pieces that need to be understood in order to construct the query.
- (1) The SELECT statement
- SELECT SalesPerson, [Oranges] AS Oranges, [Pickles] AS Pickles
- This portion of the query selects the three columns for the final result set (SalesPerson, Oranges, Pickles)
- (2) The query that pulls the raw data to be prepared
- (SELECT SalesPerson, Product, SalesAmount FROM ProductSales) ps
- This query pulls all the rows of data that we need to create the cross-tab results. The (ps) after the query is creating a temporary table of the results that can then be used to satisfy the query for step 1.
- (3) The PIVOT expression
- PIVOT (SUM (SalesAmount) FOR Product IN ( [Oranges], [Pickles]) ) AS pvt
- This query does the actual summarization and puts the results into a temporary table called pvt
Another key thing to notice in here is the use of the square brackets [ ] around the column names in both the SELECT in part (1) and the IN in part (3). These are key, because the pivot operation is treating the values in these columns as column names and this is how the breaking and grouping is done to display the data.
- Take a look at the new PIVOT option that SQL Server offers to see how you can use this
- Review the older methods that were discussed in this prior tip. These options will still work in all versions of SQL Server and may provide a better solution.
- Try to write some more complex queries to take advantage of this new option.
- Also take a look at this tip that dynamically creates the PIVOT query instead of having to hard code the query.
Last Updated: 2019-03-22
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