The difference between SQL Server char nchar varchar and nvarchar

1. char： Fixed length , Storage ansi character , Fill in the blanks .
2. nchar： Fixed length , Storage Unicode character , Fill in the blanks .
3. varchar(n)： The length is n Bytes of Variable length and not Unicode Character data of .n It has to be between 1 and 8,000 Value between . The storage size is the actual length of the bytes of the input data , instead of n Bytes .
4. nvarchar(n)： contain n A character Variable length Unicode Character data .n The value of must be between 1 And 4,000 Between . The storage size of a byte is twice the number of characters entered .
5. TEXT
   text Store variable length Not Unicode data , Maximum length is 2^31-1(2,147,483,647) Characters .
6. NCHAR、NVARCHAR、NTEXT
   These three are more than the first three in terms of names "N". and char、varchar Compare ,nchar、nvarchar Maximum storage 4000 Characters , Whether in English or Chinese ; and char、varchar It can store at most 8000 English ,4000 The Chinese characters . It can be seen that Use nchar、nvarchar Don't worry about whether the input character is English or Chinese , More convenient , But there is some loss in the amount of English stored .
   So generally speaking , If it contains Chinese characters , use nchar/nvarchar, If it's pure English and numbers , use char/varchar.