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float and real (Transact-SQL)

SQL Server 2008 R2

Approximate-number data types for use with floating point numeric data. Floating point data is approximate; therefore, not all values in the data type range can be represented exactly.

Note
The ISO synonym for real is float(24).

Data type	Range	Storage
float	- 1.79E+308 to -2.23E-308, 0 and 2.23E-308 to 1.79E+308	Depends on the value of n
real	- 3.40E + 38 to -1.18E - 38, 0 and 1.18E - 38 to 3.40E + 38	4 Bytes

Topic link icon Transact-SQL Syntax Conventions

Syntax

float [ (n) ]

Where n is the number of bits that are used to store the mantissa of the float number in scientific notation and, therefore, dictates the precision and storage size. If n is specified, it must be a value between 1 and 53. The default value of n is 53.

nvalue	Precision	Storage size
1-24	7 digits	4 bytes
25-53	15 digits	8 bytes

Note
SQL Server treats n as one of two possible values. If 1<=n<=24, n is treated as 24. If 25<=n<=53, n is treated as 53.

The SQL Server float[(n)] data type complies with the ISO standard for all values of n from 1 through 53. The synonym for double precision is float(53).

Reference

ALTER TABLE (Transact-SQL)

CAST and CONVERT (Transact-SQL)

CREATE TABLE (Transact-SQL)

Data Types (Transact-SQL)

DECLARE @local_variable (Transact-SQL)

DELETE (Transact-SQL)

INSERT (Transact-SQL)

SET @local_variable (Transact-SQL)

UPDATE (Transact-SQL)

Concepts

Data Type Conversion (Database Engine)

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