You can implicitly convert to unitext from other character and binary datatypes. You can explicitly convert from unitext to other datatypes, and vice versa. However, the conversion result is limited to the maximum length of the destination datatype. When a unitext value cannot fit the destination buffer on a Unicode character boundary, data is truncated. If you have enabled enable surrogate processing, the unitext value is never truncated in the middle of a surrogate pair of values, which means that fewer bytes may be returned after the datatype conversion. For example, if a unitext column ut in table tb stores the string “U+0041U+0042U+00c2” (U+0041 represents the Unicode character “A”), this query returns the value “AB” if the server’s character set is UTF-8, because U+00C2 is converted to 2-byte UTF-8 0xc382:
select convert(char(3), ut) from tb
Currently, the alter table modify command does not support text, image, or unitext columns as the modified column. To migrate from a text to a unitext column, you must first use bcp out to copy the existing data out, create a table with unitext columns, and then use bcp in again to place data into the new table. This migration path only works when you invoke bcp with the -Jutf8 option.
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