Question

For the case in which some of the columns are char data and other in varchar

Answer 1

Character data types that are either fixed-length, char, or variable-length, varchar. Starting with SQL Server 2019 preview, when a UTF-8 enabled collation is used, these data types store the full range of Unicode character data and use the UTF-8 character encoding. If a non-UTF-8 collation is specified, then these data types store only a subset of characters supported by the corresponding code page of that collation.