SQL Server : select columns of a table then select top 1 value - sql-server

Question

Is there a way to select columns of a table then assign the top 1 value of that column.
For example
TABLENAME | COLUMNNAME | VALUE
----------+------------+---------------
TABLE 1 | COLUMN 1 | COLUMN 1 VALUE
TABLE 1 | COLUMN 2 | COLUMN 2 VALUE
UPDATE
DECLARE #tableCOLS TABLE (tablename varchar(255) , colname varchar(255));
BEGIN
SET #MyCursor = CURSOR FOR
SELECT DISTINCT tablename FROM #tableid
OPEN #MyCursor
FETCH NEXT FROM #MyCursor
INTO #MyField2
WHILE ##FETCH_STATUS = 0
BEGIN
INSERT INTO #tableCOLS
SELECT #MyField2 , COLUMN_NAME
FROM INFORMATION_SCHEMA.COLUMNS
WHERE TABLE_NAME = #MyField2
FETCH NEXT FROM #MyCursor
INTO #MyField2
END;
CLOSE #MyCursor ;
DEALLOCATE #MyCursor;
END;
SELECT * from #tableCOLS
END;
I fetch the table columns to my dynamic table then i want to insert the value of a certain data in the columns that i fetch in my table

Answer 1

I just tested this and it works a treat
DECLARE #Result TABLE (TableName VARCHAR(50), Col VARCHAR(50), MaxValue VARCHAR(50), MaxSQL NVARCHAR(4000));
DECLARE #TableName VARCHAR(50), #Col VARCHAR(50), #MaxSQL NVARCHAR(4000), #MaxValue VARCHAR(50)
-- Load all tables and columns of interest
INSERT INTO #Result
(TableName, Col, MaxSQL)
select
object_name(object_id),
name,
'SELECT #C = MAX(' + name + ') FROM ' + object_name(object_id)
from sys.columns where object_name(object_id) = 'Table1'
-- For each row, run the dynamic SQL and update back into table
DECLARE c CURSOR FOR
SELECT TableName, Col, MaxSQL FROM #Result
OPEN c
FETCH NEXT FROM C INTO #TableName, #Col, #MaxSQL
WHILE ##FETCH_STATUS = 0
BEGIN
EXEC sp_ExecuteSQL #MaxSQL, N'#C VARCHAR(50) OUTPUT', #C = #MaxValue OUTPUT
UPDATE #Result SET MaxValue = #MaxValue WHERE TableName = #TableName AND Col = #Col;
FETCH NEXT FROM C INTO #TableName, #Col, #MaxSQL
END
CLOSE c;
DEALLOCATE c;
-- Show the results
SELECT * FROM #Result;

Answer 2

There's no need to use loops or cursors to do this. Have a look at the following...
SET NOCOUNT ON;
DECLARE #Object_id INT = OBJECT_ID('DataBaseName.Schema.TableName');
IF OBJECT_ID('tempdb..#TableCols', 'U') IS NOT NULL
DROP TABLE #TableCols;
CREATE TABLE #TableCols (
SchemaName sysname,
TableName sysname,
ColumnName sysname,
ColumnID INT NOT NULL,
Value NVARCHAR(MAX) NULL
);
INSERT #TableCols (SchemaName, TableName, ColumnName, ColumnID)
SELECT
s.name,
o.name,
c.name,
c.column_id
FROM
sys.objects o
JOIN sys.schemas s
ON o.schema_id = s.schema_id
JOIN sys.columns c
ON o.object_id = c.object_id
WHERE
o.type = 'U'
AND o.object_id = #Object_id
ORDER BY
c.column_id;
DECLARE
#CrossCols VARCHAR(MAX) = N'',
#TopVal NVARCHAR(10) = N'',
#Table sysname = N'',
#sql NVARCHAR(MAX) = N'',
#DeBug BIT = 0; -- 1 = PRINT ; 0 = EXECUTE
SELECT
#CrossCols = CONCAT(#CrossCols, N',
(', tc.ColumnID, N', CAST(t.[', tc.ColumnName, N'] AS NVARCHAR(MAX)))'),
#TopVal = tc.ColumnID,
#Table = CONCAT(tc.SchemaName, '.', tc.TableName)
FROM
#TableCols tc
ORDER BY
tc.ColumnID;
SET #sql = CONCAT(N'
UPDATE tc SET
tc.Value = t.ColumnValue
FROM
#TableCols tc
JOIN (
SELECT TOP (', #TopVal, N')
x.*
FROM
', #Table, N' t
CROSS APPLY ( VALUES', STUFF(#CrossCols, 1, 1, ''), N'
) x (ColumnID, ColumnValue)
) t
ON tc.ColumnID = t.ColumnID;')
IF #DeBug = 1
BEGIN
EXEC dbo.LongPrint #sql;
END;
ELSE
BEGIN
EXEC(#sql);
SELECT * FROM #TableCols tc;
END;

Answer 3

Give this a shot...
DECLARE #Table VARCHAR(MAX) = 'Customer'
SELECT t.name AS [Table]
, c.name AS [Column]
, cmd.mycmd
, TYPE_NAME(c.user_type_id) AS [Type]
, c.max_length AS [Size]
, CASE WHEN c.is_nullable = 1 THEN ''
ELSE 'No Nulls' END AS Nullable
, ROW_NUMBER() OVER ( PARTITION BY t.name ORDER BY c.name ASC ) AS rnk
, CASE WHEN EXISTS ( SELECT 1
FROM sys.columns c2
WHERE c2.object_id = t.object_id
AND c2.name IN ( SELECT *
FROM dbo.fnSplit('Fieldnames,ToSkip', ',') ) ) THEN 'Y'
ELSE 'N' END AS [CreModDeLs]
into #MyTempTable
FROM sys.columns AS c
JOIN sys.tables AS t ON c.object_id = t.object_id
cross apply (Select 'Select top 1 #Val = cast(' + c.name + ' as varchar(max)) from ' + t.name + ' Order by 1 desc' as mycmd) cmd
WHERE t.name LIKE #Table
ORDER BY t.name
, c.name
alter table #MyTempTable add [Id] integer identity(1,1)
alter table #MyTempTable add [Top1Val] Varchar(max)
Declare #DynamicSQL as nvarchar(1000);
Declare #dynamicparamdec nvarchar(1000) = '#val Varchar(max) Output'
Declare #valueofid as int
Declare #returnval as varchar(max)
Declare #Id integer
DECLARE #MyCursor CURSOR FAST_FORWARD
FOR
SELECT id
, mycmd
FROM #MyTempTable
where type <> 'image'
OPEN #MyCursor
FETCH #MyCursor INTO #id, #DynamicSQL
WHILE ##fetch_status = 0
BEGIN
print #dynamicsql
execute sp_executesql #DynamicSQL
, #dynamicparamdec
, #returnval output
update #MyTempTable
set Top1Val = #returnval
where id = #id
FETCH #MyCursor INTO #id, #DynamicSQL
END
--Close the cursor, if it is empty then deallocate it:
IF ( SELECT CURSOR_STATUS('global', '#MyCursor') ) >= -1
BEGIN
IF ( SELECT CURSOR_STATUS('global', '#MyCursor') ) > -1
BEGIN
CLOSE #MyCursor
END
DEALLOCATE #MyCursor
END
select * from #MyTempTable