varchar(n)

Variable length, non-Unicode character data of n bytes. n must be a number between 1 and 8,000. The storage size is the actual length in bytes of the input data, not n bytes.

nvarchar(n)

Contains n characters of variable-length Unicode character data. The value of n must be between 1 and 4,000. The storage size in bytes is twice the number of characters entered.

The two fields have field values ??respectively: me and coffee

Then the varchar field occupies 2×2+6=10 bytes of storage space, while the nvarchar field occupies 8×2= 16 bytes of storage space.

If the field value is only in English, you can choose varchar, and if the field value contains many double-byte (Chinese, Korean, etc.) characters, use nvarchar

Extended information: Microsoft Jet? database Engine? SQL data types consist of 13 basic data types, which are defined by the Microsoft Jet database engine and several validated synonyms. Common ones include: integer, single precision, double precision, variable length characters, fixed length characters, long type, date, etc.

Reference material: SQL data types