SQL FLOAT Data Type

The FLOAT data type is an approximate number with floating point data.

FLOAT value is approximate which means not all values can be represented exactly.

FLOAT(24) is identical to REAL.

Example

#

A table with 2 FLOAT columns.

CREATE TABLE DemoTable  
( 
  Id INT IDENTITY, 
  PatientName VARCHAR(100),
  Celsius FLOAT,
  Fahrenheit FLOAT
);
GO  

INSERT INTO DemoTable VALUES ('Harold Smith', 36.2, 97.16);  
INSERT INTO DemoTable VALUES ('Robert Johnson', 35.8, 96.44);  
INSERT INTO DemoTable VALUES ('Janice Lopez', 37.32, 99.176);
INSERT INTO DemoTable VALUES ('Kelly Wilson', 35.89, 96.602); 
INSERT INTO DemoTable VALUES ('Grace Taylor', NULL, NULL); 
GO  

SELECT * FROM DemoTable;
GO

DROP TABLE DemoTable;
GO
Result:  5 records
Id PatientName Celsius Fahrenheit
1 Harold Smith 36.2 97.16
2 Robert Johnson 35.8 96.44
3 Janice Lopez 37.32 99.176
4 Kelly Wilson 35.89 96.602
5 Grace Taylor NULL NULL

Syntax

#

Syntax of FLOAT.

FLOAT(number)

number -- optional, number of bits between 1 and 53 used to store the mantissa of a float number. This also defines the precision and storage size used. Default is 53.

The storage used by float depends on the precision and the number of bits value:

Number of Bits Precision Storage (bytes)
1-24 7 digits 4
25-53 15 digits 8

More Examples

FLOAT with OTHER APPROXIMATE NUMERIC TYPES

The example shows that FLOAT(24) and REAL values are identical.
CREATE TABLE DemoTable  
( 
  MyFloat FLOAT(24),
  MyReal REAL
);
GO  

INSERT INTO DemoTable VALUES (1899.982, 1899.982);  
GO  

SELECT * FROM DemoTable;
GO

DROP TABLE DemoTable;
GO
Result:  1 record
MyFloat MyReal
1899.982 1899.982

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