SQL插入语句中有单引号 && SQL中char nchar varchar nvarchar的区别 && Java中字符(串)和数值类型的转换

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A：sql 插入语句中有单引号怎么办？

Q：字符串中的单引号,一律用两个单引号表示就行了。

A：SQL中char nchar varchar nvarchar的区别是什么？

Q：http://stackoverflow.com/questions/176514/what-is-the-difference-between-char-nchar-varchar-and-nvarchar-in-sql-server

nchar and nvarchar can store Unicode characters.
char and varchar cannot store Unicode characters.
char and nchar are fixed-length which will reserve storage space for number of characters you specify even if you don't use up all that space.
varchar and nvarchar are variable-length which will only use up spaces for the characters you store. It will not reserve storage like char or nchar.
nchar and nvarchar will take up twice as much storage space, so it may be wise to use them only if you need Unicode support.

A：Java中字符(串)和数值类型的转换

Q：http://dongdong1314.blog.51cto.com/389953/79385