Can this dynamic SQL be replaced with the regular SQL to improve performance? - sql

Question

I am using the following dynamic query, but see that the performance is slow. I am not a big fan of dynamic SQL, and am looking for, if possible, a good clean and fast SQL alternative for the following. Thanks a million ton in advance! Here are some details:
In the following code, the final table missingfields_xxxx lists out the rows where we have a missing rule field.
table_name has the column rule that holds the column name of the table trans_modelname (this table can be found in the dynamic part of the sql)
DECLARE #rule NVARCHAR(MAX)
DECLARE #PeriodNumber INT = 1
DECLARE #SelectList NVARCHAR(MAX)
DECLARE #WhereList NVARCHAR(MAX)
DECLARE #SQL NVARCHAR(MAX)
DECLARE #ModelName as NVARCHAR(MAX) = 'modelname'
--DECLARE #MaxPeriods INT = 8
DECLARE #MaxPeriods INT
SELECT #MaxPeriods = count (*)
FROM
(
SELECT [rule]
FROM table_name
WHERE ModelName = #ModelName) ab
DECLARE db_cursor3 CURSOR FOR
SELECT * FROM
(
SELECT [rule]
FROM table_name
WHERE ModelName = #ModelName) cd
OPEN db_cursor3
FETCH NEXT FROM db_cursor3 INTO #rule
WHILE ##FETCH_STATUS = 0
BEGIN
BEGIN
SELECT #SelectList = COALESCE(#SelectList + ', ', '') + '' + #rule + ' AS [GLSegment_' + RIGHT('00' + CAST(#PeriodNumber AS VARCHAR), 3) + ']'
SELECT #SelectList as 'Selectlist'
IF #PeriodNumber < #MaxPeriods
BEGIN
SELECT #WhereList = COALESCE(#WhereList, '') + '(isnull([GLSegment_' + RIGHT('00' + CAST(#PeriodNumber AS VARCHAR), 3) + '],'''') = '''' ) OR '
SELECT #WhereList as 'Wherelist where periodnumber < maxperiods'
END
ELSE IF #PeriodNumber = #MaxPeriods
BEGIN
SELECT #WhereList = COALESCE(#WhereList, '') + '(isnull([GLSegment_' + RIGHT('00' + CAST(#PeriodNumber AS VARCHAR), 3) + '], '''') = '''' )'
SELECT #WhereList as 'Wherelist where periodnumber = maxperiods'
END
SET #PeriodNumber = #PeriodNumber + 1
END
FETCH NEXT FROM db_cursor3 INTO #rule
END
CLOSE db_cursor3
DEALLOCATE db_cursor3
-- build dynamic query
SET #SQL =
'SELECT * into missingfields_' + #ModelName + ' from trans_' + #ModelName + '
WHERE id in
(
SELECT id from
(
SELECT id, ' + #SelectList + '
FROM trans_' + #ModelName + ')A
WHERE ' + #WhereList + '
);
SELECT * from missingfields_' + #ModelName
PRINT #SQL
print 'missingfields_' + #ModelName
EXEC sp_executesql #SQL