If you have a situation where you want to add a column into a table in SQL Server, it would be a good idea to perform a check first if a column has already existed in a table. Otherwise, if you try to add a duplicate column, you may get an error message when you try to add a column via SQL query.
Do you need to sort comments with nested replies in SQL Server? Well this can be easily done by combining the same table using the UNION ALL join to populate the comments content. There is a trick to used to sort the comments which use the combination of a record ID field with the row number index.
Let says we have the following table structure for the comments data.
To sort the comment replies in nested order, you can use the following sql query.
DECLARE @ThreadID INT = 1 With CommentList As ( Select Comments_Parent.*, CONVERT(nvarchar(100), Row_Number() OVER ( ORDER BY Comments_Parent.CommentId )) as OrderPath FROM Comments Comments_Parent Where CommentReplyID = 0 AND ThreadID = @ListingID AND Approved = 1 UNION ALL SELECT Sub_Comments.*, CONVERT(nvarchar(100), CL.OrderPath + '.' + Cast( Row_Number() over ( order by Sub_Comments.CommentId ) as nvarchar(100))) As CommentLevel FROM Comments Sub_Comments INNER JOIN CommentList CL ON Sub_Comments.CommentReplyID = CL.CommentID WHERE Sub_Comments.Approved = 1 ) SELECT * FROM CommentList ORDER BY CONVERT(INT,SUBSTRING (CommentLevel, CASE WHEN charindex('.',CommentLevel,0)=0 THEN 1 ELSE 0 END, CASE WHEN charindex('.',CommentLevel,0)=0 THEN LEN(CommentLevel) else charindex('.',CommentLevel,0) end ))