PostgreSQL Create new table out of rows - sql

Question

I am using PostgreSQL 9.1
I have the following table containing some settings
setting | content
---------------+---------
enabled | True
reenable_time | 1
count_row | 6
count_col | 3
(4 rows)
And I want to have something like this
enabled | reenable_time | count_row | count_col
---------+-----------------+-------------+----------
True | 1 | 6 | 3
(1 row)
Thank you for your answers!

Answer 1

What you need is cross-tabulation (pivoting), aka turning rows into columns.
If you don't want to hardcode "enabled", "reenable_time", etc., you need to use dynamic SQL.
The basic idea goes like this:
SELECT -- Grab the user_account columns.
acc.id,
acc.email,
-- Use max() combined with a case statement to
-- usher individual attribute values into columns.
max(CASE WHEN (attr.attribute_type = 'first-name')
THEN attr.value END) AS fname,
max(CASE WHEN (attr.attribute_type = 'last-name')
THEN attr.value END) AS lname,
max(CASE WHEN (attr.attribute_type = 'title')
THEN attr.value END) AS title
FROM user_account AS acc
-- Join the attribute table /once/.
LEFT JOIN user_attribute AS attr
ON (attr.user_account_id = acc.id)
WHERE (acc.email = 'foo#example.com')
-- Group by the non-pivoted columns
GROUP BY acc.id,acc.email;
Here a link for further information:
https://sykosomatic.org/2011/09/pivot-tables-in-postgresql/
Here an example from my workplace (it's MS-SQL, but you'll get the idea, PostGre doesn't support the pivot command, it's MS proprietary, so you need to use "case when" with "group by"):
-- ===================================================
-- Author: Stefan Steiger
-- Create date: 14.04.2011
-- Last modified: 17.01.2012
-- Description: Übersetzung für Berichte
-- ===================================================
CREATE PROCEDURE [dbo].[sp_RPT_Report_Translation]
#in_mandant varchar(3)
,#in_sprache varchar(2)
,#in_stichtag varchar(50)
,#in_report_name nvarchar(1000)
AS
BEGIN
DECLARE
#strSQL NVARCHAR(MAX)
,#strReportName NVARCHAR(1000)
,#strPivotColumns NVARCHAR(MAX)
,#stichtag DATETIME
-- Abrunden des Eingabedatums auf 00:00:00 Uhr
SET #stichtag = CONVERT(DATETIME, #in_stichtag)
SET #stichtag = CAST(FLOOR(CAST(#stichtag AS Float)) AS DateTime)
SET #in_stichtag = CONVERT(varchar(50), #stichtag)
SET NOCOUNT ON;
SET #strReportName = REPLACE(#in_report_name, N'''', '''''')
-- http://geekswithblogs.net/baskibv/archive/2008/07/03/123567.aspx
SELECT
#strPivotColumns = COALESCE(#strPivotColumns, '') + '[' + [RTR_ItemCaption] + '], '
FROM T_RPT_Translations
WHERE (RTR_Status = 1)
AND (RTR_MDT_ID = #in_mandant)
AND
(
(RTR_ReportName = #strReportName)
OR
(RTR_ReportName = 'PARA_ALL')
)
--AND (RTR_ItemCaption != 'RPT_Title')
AND (RTR_ItemCaption IS NOT NULL)
AND
(
(RTR_IsFlag != 1)
OR
(RTR_IsFlag IS NULL)
)
AND (RTR_ItemCaption != '')
ORDER BY RTR_Sort
SET #strPivotColumns = SUBSTRING(#strPivotColumns, 0, LEN(#strPivotColumns))
SET #strPivotColumns = REPLACE(#strPivotColumns, N'''', '''''')
--PRINT #strPivotColumns
SET #strSQL = '
SELECT TOP(1) * FROM
(
SELECT
RTR_ItemCaption
--,RTR_Kurz_' + #in_sprache + '
,RTR_Lang_' + #in_sprache + '
FROM T_RPT_Translations
WHERE (RTR_MDT_ID = ''' + #in_mandant+ ''')
AND
(
(RTR_ReportName = ''' + #strReportName + ''')
OR
(RTR_ReportName = ''PARA_ALL'')
)
--AND (RTR_ItemCaption != ''RPT_Title'')
AND (RTR_Status = 1)
AND (RTR_ItemCaption IS NOT NULL)
AND
(
(RTR_IsFlag != 1)
OR
(RTR_IsFlag IS NULL)
)
AND (RTR_ItemCaption != '''')
) AS SourceTable
PIVOT
(
MAX(RTR_Lang_' + #in_sprache + ')
FOR RTR_ItemCaption IN
( '
+ #strPivotColumns +
' )
) AS PivotTable
--ORDER BY RPT_RM_SO_Bezeichnung, RPT_RM_GB_Bezeichnung, RPT_RM_NutzungGruppeCode
'
DECLARE #ProzedurParameter nvarchar(max)
SET #ProzedurParameter = '
DECLARE #in_mandant varchar(3)
,#in_sprache varchar(2)
,#in_stichtag varchar(50)
,#in_report_name nvarchar(1000)
;
SET #in_mandant = ''' + REPLACE(#in_mandant, '''', '''''') + ''';
SET #in_sprache = ''' + REPLACE(#in_sprache, '''', '''''') + ''';
SET #in_stichtag = ''' + REPLACE(#in_stichtag, '''', '''''') + ''';
SET #in_report_name = ''' + REPLACE(#in_report_name, '''', '''''') + ''';
'
EXECUTE sp_RPT_DEBUG_LOG_ProzedurRun
'sp_RPT_Report_Translation'
,#ProzedurParameter
,#strSQL
,'' --#ProzedurDetail
;
--PRINT #strSQL
EXECUTE (#strSQL)
END
GO