Convert Rows to Columns in SQL Server using PIVOT

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Ever wondered how to convert data from rows to columns in SQL Server. I am talking about a query that can transform records from multiple rows into columns. Using PIVOT, we can efficiently rotate a table's data to show a summarized result in columns.

What is PIVOT in SQL Server?

PIVOT is used to turn or rotate data in a table by converting unique values extracted from a single column and show the result in multiple columns.

See this image.

Convert rows into columns using SQL Server Pivot

Let's see an example.

As usual, I'll use the dbo.Books table for the example. The table has five columns and few rows in it. Create the table and insert the records in it.

Also, check this list of popular SQL Server post in this blog.

PIVOT Using Aggregate function

I'll PIVOT (meaning, rotate or turn) the Books table to get the max price for each distinct category. The T-SQL aggregate MAX() function will return the maximum value from a list of values in a column.

SELECT Computers, Science, Programming, Business
FROM (
  SELECT Price, Category FROM dbo.Books
) Books
PIVOT ( 
    MAX(Price) FOR Category IN (Computers, Science, Programming, Business)
) Result;

The output will look like,

Computers 
125.60
Science
210.40
Programming
56.00
Business
150.70

Similarly, we can get the total price for each category using PIVOT and SUM() function.

SELECT Computers, Science, Programming, Business
FROM (
  SELECT Price, Category FROM dbo.Books
) Books
PIVOT (
  SUM(Price) FOR Category IN (Computers, Science, Programming, Business)
) Result;

Output

Computers
187.80
Science
759.05
Programming
56.00
Business
150.70

The queries above have one similarity (other than using PIVOT), which is, it uses pre-defined values as column name (Computer, Science etc.). We looked for "unique" values in "Category" column and used the list in our query as columns.

Now, an obvious question that comes to our mind. How do we PIVOT a table if we do not know the values for our columns? It is not always wise to hardcore values as columns. Since, categories might change in the Books table or we add new categories to the list.

You may also like this post (a simple SQL trick): How to Insert multiple rows with a single INSERT statement in SQL Server?

PIVOT using Dynamically extracted Columns

This may also be called as Dynamic PIVOT, where values for columns are extracted dynamically using an SQL query, at runtime.

We will first extract all the Distinct categories from the table and store the result in a variable. Each value is separate by a comma.

DECLARE @Category AS VARCHAR(MAX)
SELECT @Category =
    COALESCE(@Category + ', ', '') + CAST(Category AS VARCHAR(20)) 
    FROM (SELECT DISTINCT Category FROM dbo.Books) Books
SELECT @Category Categories

Output

Category
Business, Computers, Programming, Science
We got the values for our columns, all separate by a comma. Using the above result, we will now create the Dynamic PIVOT. The syntax remains the same as we did in Static PIVOT, except that we will add the variable @Columns inside the query and execute it as we execute a Stored Procedure.

Also read... 👉 How to Convert rows into columns and SAVE the data in a table.
Convert rows to columns and save data

DECLARE @Category AS VARCHAR(MAX)
SELECT @Category =
    COALESCE(@Category + ', ', '') + CAST(Category AS VARCHAR(20)) 
    FROM (SELECT DISTINCT Category FROM dbo.Books) Books
DECLARE @DynamicPIVOT AS VARCHAR(MAX)
SELECT @DynamicPIVOT = 'SELECT ' + @Category +
' FROM (
    SELECT Price, Category FROM dbo.Books
) Books
PIVOT (
    MAX(Price) FOR Category IN (' + @Category + ')
) Result;'

EXEC (@DynamicPIVOT)

Output

Business 
150.70
Computers
125.60
Programming
56.00
Science
210.40
Conclusion

The PIVOT operator is available in SQL Server 2005 and above. It simplifies the process of transforming data from rows to columns, where we use the row’s values as column headers. PIVOT usually works with aggregate functions, such as MAX(), SUM() etc.

Finally if you want, you can also save the PIVOT result in a Table.

Happy coding.

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2) How to convert Rows into Columns using SQL Server PIVOT OR how to use PIVOT in SQL Server: Ever wondered how you can convert data from rows to columns in SQL Server. We are talking about an SQL query, which will transform records from multiple rows into columns. Using SQL Server PIVOT, we can efficiently rotate a table’s data to show a summarized result.

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