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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. The ISO synonym for
real
is
float(24)
.
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
.
n
value
Precision
Storage size
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)
.
To view Transact-SQL syntax for SQL Server 2014 and earlier, see
Previous versions documentation
.
Data type
Range
Storage
Converting float and real data
Values of
float
are truncated when they are converted to any integer type.
When you want to convert from
float
or
real
to character data, using the STR string function is usually more useful than CAST( ). This is because STR enables more control over formatting. For more information, see
STR (Transact-SQL)
and
Functions (Transact-SQL)
.
Prior to SQL Server 2016 (13.x), conversion of
float
values to
decimal
or
numeric
is restricted to values of precision 17 digits only. Any
float
value less than 5E-18 (when set using either the scientific notation of 5E-18 or the decimal notation of 0.000000000000000005) rounds down to 0. This is no longer a restriction as of SQL Server 2016 (13.x).
See also
ALTER TABLE (Transact-SQL)
CAST and CONVERT (Transact-SQL)
CREATE TABLE (Transact-SQL)
Data Type Conversion (Database Engine)
Data Types (Transact-SQL)
DECLARE
@local_variable
(Transact-SQL)
SET
@local_variable
(Transact-SQL)
