Need all columns on one row - sql

Question

I wrote the following query:
IF OBJECT_ID ('tempdb..#ColumnsType') IS NOT NULL DROP TABLE #ColumnsType
DECLARE #vQuery NVARCHAR(MAX) =''
IF OBJECT_ID ('tempdb..#random') IS NOT NULL DROP TABLE #random
CREATE TABLE #random (
ColumnID INT PRIMARY KEY IDENTITY(1,1) NOT NULL
, randomname VARCHAR(50)
, randomvalue INT)
INSERT INTO #random (randomname, randomvalue)
VALUES ('a3', 123)
, ('bla', 4325)
, ('another_bla', 5643)
, ('end_here', 3)
select *
from #random
CREATE TABLE #ColumnsType (
ColumnID INT PRIMARY KEY IDENTITY(1,1) NOT NULL
, ColumnName sysname
, DataType sysname
)
INSERT INTO #ColumnsType (ColumnName, DataType)
SELECT [name],
system_type_id
FROM Tempdb.Sys.Columns
WHERE Object_ID = Object_ID('tempdb..#random')
AND system_type_id = 56
DECLARE #i INT = (SELECT MIN(ColumnID) FROM #random);
DECLARE #maxId INT = (SELECT MAX(ColumnID) FROM #random);
DECLARE #ColumnName VARCHAR(200);
DECLARE #DataType VARCHAR(200);
WHILE #i <= #maxId
BEGIN
SET #ColumnName = (SELECT ColumnName FROM #ColumnsType WHERE ColumnId = #i)
-- SET #DataType = (SELECT DataType FROM #ColumnsType WHERE ColumnId = #i)
SELECT #vQuery =
'SELECT
MIN(TRY_CONVERT(NUMERIC(30, 4), ' +#ColumnName+ ')) AS ' +#ColumnName+ '_MinValue
, MAX(TRY_CONVERT(NUMERIC(30, 4), ' +#ColumnName+ ')) AS ' +#ColumnName+ '_MaxValue
, AVG(TRY_CONVERT(NUMERIC(30, 4), ' +#ColumnName+ ')) AS ' +#ColumnName + '_AvgValue
, STDEV(TRY_CONVERT(NUMERIC(30, 4), ' +#ColumnName+ ')) AS ' +#ColumnName+ '_StandardDeviation
, SUM(TRY_CONVERT(NUMERIC(30, 4), ' +#ColumnName+ ')) AS ' +#ColumnName+ '_TotalSum
FROM tempdb..#random' -- +#Schema+'.'+#Table+ ''
EXEC sp_executesql #vQuery
PRINT #vQuery
SET #i = #i + 1
END
For the sake of demonstration I create temp table with random values. I perform profiling on part of the columns which are consisting only of numeric values. To filter the columns I get their names and filter by type, using Tempdb.Sys.Columns. In normal case with my original data, I use INFORMATION_SCHEMA.COLUMNS but I think this is not that important.
The query returns the following:
The result is presented on two rows. What I'd like to do is to have this result on one row. The idea is to pivot the one row result after and to receive the following result:

Answer 1

As I mentioned, you need to not use a loop, use a set based method and UNION ALL your dynamic statements. I assume here, as well, that you are using a recent version of SQL Server. If not, you'll need to replace STRING_AGG with the old FOR XML PATH (and STUFF) method.
This should be enough to get you started:
USE Sandbox;
GO
CREATE TABLE dbo.YourTable (Col1 int,
Col2 varchar(10));
GO
DECLARE #SchemaName sysname = N'dbo',
#TableName sysname = N'YourTable';
DECLARE #SQL nvarchar(MAX),
#CRLF nchar(2) = NCHAR(13) + NCHAR(10);
DECLARE #Delimiter nvarchar(50) = #CRLF + N'UNION ALL' + #CRLF;
SELECT #SQL = STRING_AGG(CONVERT(nvarchar(MAX),N'SELECT MIN(') + QUOTENAME(c.[name]) + N') AS ' + QUOTENAME(c.[name] + N'_MIN') + N',' + #CRLF +
N' MAX(' + QUOTENAME(c.[name]) + N') AS ' + QUOTENAME(c.[name] + N'_MAX') + #CRLF +
N'FROM ' + QUOTENAME(s.[name]) + N'.' + QUOTENAME(t.[name])
,#Delimiter) WITHIN GROUP (ORDER BY c.column_id)
FROM sys.schemas s
JOIN sys.tables t ON s.schema_id = t.schema_id
JOIN sys.columns c ON t.object_id = c.object_id
WHERE s.[name] = #SchemaName
AND t.[name] = #TableName
PRINT #SQL;
EXEC sys.sp_executesql #SQL;
GO
DROP TABLE dbo.YourTable;

Answer 2

Here is a very clean and nice solution which is what I was looking for:
I choose the columns, from specific table, scan it once and perform multiple calculations on it
I use dynamic query and make it one statement for all columns.
It works really fast. It took a little over 5 minutes to return result for table with 50 mil rows.
The only thing that is left to do is to UNPIVOT in order to insert results in a table that I want.
DECLARE
#q1 NVARCHAR(MAX)
, #q2 NVARCHAR(MAX)
, #q3 NVARCHAR(500)
, #schema VARCHAR(50) = '' -- choose schema
, #table VARCHAR(200) = '' -- choose table
SET #Q1 = 'SELECT ' + '''' + #table + '''' + ' as tableName, '
SET #Q3 = ' FROM ' + #schema + '.' + #table
SELECT #q2 = COALESCE(#q2 + ', ', '')
+ ' max(' + columnName + ') as ' + columnName + '_max, '
+ ' min(' + columnName + ') as ' + columnName + '_min, '
+ ' avg(' + columnName + ') as ' + columnName + '_avg, '
+ ' stdev(' + columnName + ') as ' + columnName + '_stdev, '
+ ' sum(' + columnName + ') as ' + columnName + '_sum '
FROM (
SELECT s.[name] as schemaName, t.[name] as tableName, c.[name] as columnName, st.[name] as typeName
FROM sys.schemas s
INNER JOIN sys.tables t ON s.schema_id = t.schema_id
INNER JOIN sys.columns c ON t.object_id = c.object_id
INNER JOIN sys.types st ON st.user_type_id = c.user_type_id
WHERE 1=1
AND s.[name] = #schema
AND t.[name] = #table
AND st.[name] IN ('') -- choose columns of specific data type, that you want to profile
) data
SELECT #q1 = #q1 + #q2 + #q3
EXEC sys.sp_executesql #Q1
Enjoy!