float and real (Transact-SQL)
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).
Applies to: SQL Server (SQL Server 2008 through current version), Azure SQL Database.
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 Built-in Functions (Transact-SQL).
Conversion of float values that use scientific notation to decimal or numeric is restricted to values of precision 17 digits only. Any value with precision higher than 17 rounds to zero.