In SQL, the term "float" refers to a data type that represents real numbers - numbers with fractional components. It's akin to the double data type in other programming languages. Floats are used to store and manipulate numerical data that includes decimals, or any number not represented by integers.
For instance, consider we have an order table in a SQL database. In this table, we may have fields for quantity ordered, total cost, and cost per item. While the quantity ordered could be an integer, total cost and cost per item would require floating-point precision. Here, float data type would come into play.
Float Data Types in SQL
SQL provides two types of floating-point data types, each serving a slightly different purpose:
Float(S,p)
The basic floating-point data type is float(S, p). Here, S denotes the storage size (4 or 8 bytes) and p is the total number of digits after the decimal point. The maximum number of digits before the decimal point is S - p - 1.
.Standard Float Data Types
Several databases set default values for S and p (usually 8 for S and 15 for p) in the float data type. These default values are generally suitable for most applications.
Confine your use to situations where you require specific precision and can trade off storage size. Storing integers as floats, for example, can waste memory and CPU power.
Float Precision
Initially, the float data type was only able to store eight bytes. SQL has since introduced a 16-byte extended precision floating-point type, known as real or float8, often referred to as double precision.
Double precision adds extra storage and CPU resources but provides greater accuracy, especially in the mantissa and decimal parts of the number.
Remember, SQL databases have different naming conventions for these data types. Microsoft's SQL Server uses the 'float' alias for any non-default-sized floating types, while MySQL uses the name 'float' for the default 4-byte floating-point type and the name 'double' for the 8-byte type.
