Convert from One Character Type to Another

When converting from a multibyte character set to a single-byte character set, characters with no single-byte equivalent are converted to question marks.

You can explicitly convert text and unitext columns to char, nchar, varchar, unichar, univarchar, or nvarchar. You are limited to the maximum length of the character datatypes, which is determined by the maximum column size for your server’s logical page size. If you do not specify the length, the converted value has a default length of 30 bytes.