CODEWITHSUNDEEP
sqlsql-server
Bret Shandro
Bret Shandro

Reputation: 61

How to build a query that SELECT rows into columns for SQL?

How can I write a query in SQL Server that returns a column for each variable of each unique ID? Below is a simplified example of what I am trying to accomplish. Would you be able to point me in the right direction?

Table_Exists

ID    |    LOCATION    |    STATUS
__________________________________
001   |     top        |     3
001   |     mid        |     1
001   |     bot        |     4
002   |     top        |     2
002   |     mid        |     2
002   |     bot        |     1
003   |     top        |     1
003   |     mid        |     4
003   |     bot        |     2

Here is a simplified example of what I am trying, obviously without success. The code below returns an error message for incorrect syntax around '=':

SELECT  
  ID,
  LOCATION = top AS Top,
  LOCATION = mid AS Middle,
  LOCATION = bot AS Bottom
FROM 
  Table_Exists

I trying to build:

Table_Desired

ID | Top | Middle | Bottom 
__________________________
001|  3  |   1    |  4
002|  4  |   2    |  2 
003|  1  |   4    |  2

Upvotes: 2

Views: 112

Answers (2)

Lukasz Szozda
Lukasz Szozda

Reputation: 175646

You can use self join (as long as your LOCATION is NOT NULL and it contains all top/mid/bot values):

 SELECT t1.ID, t1.Status AS Top, t2.Status AS Middle, t3.Status AS Bottom
 FROM Table_Exists t1
 JOIN Table_Exists t2
   ON t1.ID = t2.ID
  AND t1.LOCATION = 'top'
  AND t2.Location = 'mid'
 JOIN Table_Exists t3
   ON t1.ID = t3.ID
  AND t1.LOCATION = 'top'
  AND t3.Location = 'bot';

LiveDemo

For more generic solution use PIVOT:

SELECT
     [ID]
    ,[Top]    = [top] 
    ,[Middle] = [mid]
    ,[Bottom] = [bot]
FROM #Table_Exists t
PIVOT (
   MAX(STATUS) FOR LOCATION IN ([top],[mid],[bot])
) AS Piv

LiveDemo2

Upvotes: 3

G.Maltby
G.Maltby

Reputation: 66

Use pivot function like this

SELECT
    ID,
    [top] AS [Top],
    [mid] AS Middle,
    [bot] AS Bottom
FROM(SELECT 
    ID, 
    LOCATION,
    STATUS
FROM 
    Table_Exists) AS SourceTable
PIVOT (AVG(STATUS) FOR LOCATION IN ([top],[mid],[bot])) AS PivotTable

Upvotes: 2

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