PIVOT Query in SQL

Introduction

This is a very simple example of Pivot query for the beginners. We use pivot queries when we need to transform data from row-level to columnar data.

Pivot query help us to generate an interactive table that quickly combines and compares large amounts of data. We can rotate its rows and columns to see different summaries of the source data, and we can display the details for areas of interest at a glance. It also help us to generate Multidimensional reporting.

Background

This post intends to help T-SQL developers get started with PIVOT queries. Most business applications will need some sort of PIVOT queries and I am sure many of you must have come across pivoting requirements several times in the past. 

Using the Code

Let us have a table name Invoice which has three properties, InvoiceNumber, InvoiceDate,InvoiceAmount. Suppose we have several rows input in the table. Our goal is to display the sum ofInvoiceAmount each month.

SELECT * FROM (SELECT year(invoiceDate) as [year], left(datename(month,invoicedate),3)as [month], _
InvoiceAmount as Amount FROM Invoice) as InvoiceResult 

SELECT *
FROM (
    SELECT 
        year(invoiceDate) as [year],left(datename(month,invoicedate),3)as [month], 
        InvoiceAmount as Amount 
    FROM Invoice
) as s
PIVOT
(
    SUM(Amount)
    FOR [month] IN (jan, feb, mar, apr, 
    may, jun, jul, aug, sep, oct, nov, dec)
)AS pivot