Dynamic SQL - Picking the values from the temp table - sql

Question

I have a temp table that has the following information.
TableName ColumnName PrimaryKeyColumnName Primarykey(A GUID)
(4 columns)
I need to include one more new column Value that should grab data based on the condition below
"for each row in the temp table"
select ColumnName from TableName where PrimaryKeyColumnName = Primarykey
To be even more precise , the query must retrieve the values from the table directly.
I am sure this can be achieved using cursor. But it might impact my query performance.
Could this be achieved using sp_sqlexecute? I tried converting the query as a varchar.
Like this
set #sql = 'select '+ #final.[primary field] +'from ' + #final.tablename +
'where '+ #final.PrimaryKeyColumnName + '='+ #final.Primarykey
exec sp_sqlexecute #sql

Answer 1

Possible this be helpful for you -
IF OBJECT_ID('tempdb.dbo.#temp') IS NOT NULL
DROP TABLE #temp
GO
CREATE TABLE #temp
(
[primary field] SYSNAME,
tablename SYSNAME,
PrimaryKeyColumnName SYSNAME,
Primarykey SYSNAME
)
INSERT INTO #temp ([primary field], tablename, PrimaryKeyColumnName, Primarykey)
VALUES
('[column1]','[table1]','[column3]', '[column12]'),
('[column2]','[table2]','[column4]', '[column24]')
DECLARE #SQL NVARCHAR(MAX)
SET #SQL = (
SELECT CHAR(13) + 'SELECT '+ [primary field] + ' FROM ' + tablename +
' WHERE '+ PrimaryKeyColumnName + ' = '+ Primarykey
FROM #temp
FOR XML PATH(''), TYPE).value('.', 'NVARCHAR(MAX)')
PRINT #SQL
--EXEC sys.sp_executesql #SQL
Output -
SELECT [column1] FROM [table1] WHERE [column3] = [column12]
SELECT [column2] FROM [table2] WHERE [column4] = [column24]

Answer 2

I am not sure that I understood what you are trying to do but try this:
declare #sql varchar(8000);
set #sql = null;
select #sql =
coalesce(#sql+' union all select '+ColumnName+' from '+ tablename,
'select '+ColumnName+' from '+ tablename)
from final where ColumnName = PrimaryKeyColumnName;
exec sp_sqlexecute #sql;
Notice that the #sql is limited -in my sample 8000- if the temp table you have is too big you gonna have to make a separate executes,needs some changes in the code.
Always you have to set an initial value for #SQL as null.
I think no need for cursor, this will be solved using some SQL tricks.
Hope this will help...

Answer 3

Create Table #tempValueFetch
(
TableName sysname,
PrimaryKeyColumnName sysname,
AttributeColumnName sysname,
Primaryfield sysname,
PrimaryKey sysname,
Label nvarchar(max),
Value nvarchar(max)
)
this temp table has been populated with 5 columns namely TableName,PrimaryKeyColumnName,AttributeColumnName ,Primaryfield ,PrimaryKey
The columns label and value has to updated dynamically.Note that primary key is a uniqueidentifier