string datatype

Question

What's the difference bewteen string datatype char and nchar ?
And what's the difference between string literal with single quote only 'xxx' and with an leading N letter N'xxx' ?

Answer 1

Here is detail on these datatypes:

nchar/nvarchar:
http://msdn.microsoft.com/library/en-us/tsqlref/ts_na-nop_9msy.asp

char/varchar:
http://msdn.microsoft.com/library/en-us/tsqlref/ts_ca-co_7tpu.asp

Answer 2

The n prefix for data types means the data type is unicode. Unicode supports a wider range of characters and more space is needed to store Unicode characters.

 A preceding n in a string literal make it a unicode constant.