how to invert a table (something called pivot in t-sql)

Please start any new threads on our new site at https://forums.sqlteam.com. We've got lots of great SQL Server experts to answer whatever question you can come up with.

All Forums

Old Forums

CLOSED - General SQL Server

how to invert a table (something called pivot in t-sql)

Author

Topic

AskSQLTeam
Ask SQLTeam Question

0 Posts

Posted - 2003-08-20 : 07:53:37

mrlace2 writes "How can use T-SQL to invert this table

gbit1 gbit2 gbit3
100 200 300
100 200 300

to into this table

gbit1 100
gbit2 200
gbit3 300"

harshal_in
Aged Yak Warrior

633 Posts

Posted - 2003-08-20 : 08:27:22

From BOL:Cross-Tab Reports
Sometimes it is necessary to rotate results so that columns are presented horizontally and rows are presented vertically. This is known as creating a PivotTable®, creating a cross-tab report, or rotating data.

Assume there is a table Pivot that has one row per quarter. A SELECT of Pivot reports the quarters vertically:

Year Quarter Amount
---- ------- ------
1990 1 1.1
1990 2 1.2
1990 3 1.3
1990 4 1.4
1991 1 2.1
1991 2 2.2
1991 3 2.3
1991 4 2.4

A report must be produced with a table that contains one row for each year, with the values for each quarter appearing in a separate column, such as:

Year
Q1
Q2
Q3
Q4

1990
1.1
1.2
1.3
1.4

1991
2.1
2.2
2.3
2.4

These are the statements used to create the Pivot table and populate it with the data from the first table:

USE Northwind
GO

CREATE TABLE Pivot
( Year SMALLINT,
Quarter TINYINT,
Amount DECIMAL(2,1) )
GO
INSERT INTO Pivot VALUES (1990, 1, 1.1)
INSERT INTO Pivot VALUES (1990, 2, 1.2)
INSERT INTO Pivot VALUES (1990, 3, 1.3)
INSERT INTO Pivot VALUES (1990, 4, 1.4)
INSERT INTO Pivot VALUES (1991, 1, 2.1)
INSERT INTO Pivot VALUES (1991, 2, 2.2)
INSERT INTO Pivot VALUES (1991, 3, 2.3)
INSERT INTO Pivot VALUES (1991, 4, 2.4)
GO

This is the SELECT statement used to create the rotated results:

SELECT Year,
SUM(CASE Quarter WHEN 1 THEN Amount ELSE 0 END) AS Q1,
SUM(CASE Quarter WHEN 2 THEN Amount ELSE 0 END) AS Q2,
SUM(CASE Quarter WHEN 3 THEN Amount ELSE 0 END) AS Q3,
SUM(CASE Quarter WHEN 4 THEN Amount ELSE 0 END) AS Q4
FROM Northwind.dbo.Pivot
GROUP BY Year
GO

This SELECT statement also handles a table in which there are multiple rows for each quarter. The GROUP BY combines all rows in Pivot for a given year into a single row in the output. When the grouping operation is being performed, the CASE functions in the SUM aggregates are applied in such a way that the Amount values for each quarter are added into the proper column in the result set and 0 is added to the result set columns for the other quarters.

If the results of this SELECT statement are used as input to a spreadsheet, it is easy for the spreadsheet to calculate a total for each year. When the SELECT is used from an application it may be easier to enhance the SELECT statement to calculate the yearly total. For example:

SELECT P1.*, (P1.Q1 + P1.Q2 + P1.Q3 + P1.Q4) AS YearTotal
FROM (SELECT Year,
SUM(CASE P.Quarter WHEN 1 THEN P.Amount ELSE 0 END) AS Q1,
SUM(CASE P.Quarter WHEN 2 THEN P.Amount ELSE 0 END) AS Q2,
SUM(CASE P.Quarter WHEN 3 THEN P.Amount ELSE 0 END) AS Q3,
SUM(CASE P.Quarter WHEN 4 THEN P.Amount ELSE 0 END) AS Q4
FROM Pivot AS P
GROUP BY P.Year) AS P1
GO

The Judgement of the Judge is as good as the Judge.

robvolk
Most Valuable Yak

15732 Posts

Posted - 2003-08-20 : 13:27:42

Actually, you want to un-pivot your table. This should help:

http://www.sqlteam.com/forums/topic.asp?TOPIC_ID=3914

Subscribe to SQLTeam.com

SQLTeam.com Articles via RSS

SQLTeam.com Weblog via RSS

- Advertisement -

Resources