SQL Server re-learning (1) -- Differences Between varchar, nvarchar, and char, varcharnvarchar

SQL Server re-learning (1) -- Differences Between varchar, nvarchar, and char, varcharnvarchar

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Character data with a variable length of n Bytes and non-Unicode length. N must be a value between 1 and 8,000. The storage size is the actual length of the input data bytes, rather than n Bytes. Nvarchar (n) contains variable-length Unicode characters of n characters. The value of n must be between 1 and 4,000. The storage size of bytes is twice the number of input characters. The two fields have Field Values: I and coffee, so the varchar field occupies 2 × 2 + 6 = 10 bytes of storage space, the nvarchar field occupies 8 × 2 = 16 bytes of storage space.
If the field value is only in English, you can select varchar. If the field value contains many double-byte (Chinese, Korean, etc.) characters, use nvarchar. If the char length is insufficient, use spaces.
Error example: If char is used for storing the user name, if the length is not enough for comparison, for example, if the length of "admin" is 5, it is set to char (10 ), there will be five spaces after the retrieved admin.

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