How to port LTRIM from Oracle to SQL Server?

Yeehaw.

DECLARE @MyTable TABLE ( MyColumn VARCHAR(100) );

INSERT @MyTable ( MyColumn )
    VALUES ( '-----, ,,, This is ,- a test,---,' );

SELECT *, 
        SUBSTRING(mt.MyColumn, ca.p, LEN(mt.MyColumn))
FROM @MyTable AS mt
CROSS APPLY ( SELECT * 
              FROM (VALUES (PATINDEX ('%[^ ,-]%', MyColumn))
            ) AS x (p) ) AS ca;

Take the suffix of the string starting from the first character which is not a space, comma or hyphen:

declare @str varchar(100) = '   -----, ,,, This is ,- a test,---,'

select  substring(@str,patindex('%[^ ,-]%',@str),len(@str))

Result:

This is ,- a test,---,

Please note that the hyphen, since it is a special character in regular expressions meaning 'range' (e.g. [a-z]), must be either first ([^- ,]) or last ([^ ,-]).

I don't think you'll be happy with this solution compared to Oracle's ltrim but it does what you want.

declare @Pattern varchar(32) = '-, ';

select case when MyColumn like '['+@Pattern+']%'
         then right(MyColumn
          , len(MyColumn)-(patindex('%[^'+@Pattern+']%',MyColumn)-1)
          )
       else MyColumn
       end
from MyTable

rextester: http://rextester.com/IXOL62563