Try this:
DECLARE @SUM VARCHAR(50)='33.90';
SELECT CAST(CAST(LEFT(@SUM,CHARINDEX('.',@SUM,0)-1) AS INT)+
CAST(SUBSTRING(@SUM,CHARINDEX('.',@SUM,0)+1,LEN(@SUM))
AS INT)/60 AS VARCHAR(10))+'.'+
CAST(CAST(SUBSTRING(@SUM,CHARINDEX('.',@SUM,0)+1,LEN(@SUM))
AS INT)%60 AS VARCHAR(10))
result:
34.30
1
solved How to convert the Varchar of sum to time using sql server 2008 [closed]