Microsoft SQL Server 中的小数数据类型

g87616758

　　
　　
From MSDN:

　　float and real
　　Approximate number data types for use with floating point numeric data. Floating point data is approximate; not all values in the data type range can be precisely represented.
Syntax
　　float [ ( n ) ]
　　Is a floating point number data with the following valid values: - 1.79E + 308 through -2.23E - 308, 0 and 2.23E -308 through 1.79E + 308. n is the number of bits used to store the mantissa of the float number in scientific notation and thus dictates the precision and storage size. n must be a value from 1 through 53. The default value of n is 53.
n is Precision Storage size1-247 digits4 bytes25-5315 digits8 bytes
　　The Microsoft® SQL Server™ float[(n)] data type conforms to the SQL-92 standard for all values of n from 1 to 53. The synonym for double precision is float(53).
　　real
　　Is a floating point number data with the following valid values: –3.40E + 38 through -1.18E - 38, 0 and 1.18E - 38 through 3.40E + 38. Storage size is 4 bytes. In SQL Server, the synonym for real is float(24).
Note  Microsoft® SQL Server™ 2000 treats n as one of two possible values. If 1