Concatenation of strings by for xml path

Question

Hi! Today I learned for xml path technique to concatenate strings in mssql. Since I\'ve never worked with xml in mssql and google hasn\'t helped, I need to ask

Answer 1

Ok, so I haven't been completely satisfied the way Gordon Linoff suggested and since I've found this kind of problem actual for me I'm adding here another solution without using for xml path:

declare
    @pivot_sequence nvarchar(max),
    @columns_sequence nvarchar(max)

select
    @pivot_sequence = coalesce(@pivot_sequence + ', [', '[') 
        + col_name + ']',
    @columns_sequence = coalesce(@columns_sequence + ', ', '')
        + 'isnull([' + col_name + '], 0) as [' + col_name + ']'
from some_table
order by
    /* some_columns if needed to order concatenation */

Obviously, it'll work much slower but in cases when you haven't many rows it won't drastically affect on performance. In my case I have dynamic pivot query and these strings are built for it - I won't have many columns in pivot so it's fine for me.