12.25 Precision Math

SQL modes that control how strict the server is about accepting or rejecting invalid data.

The MySQL library for fixed-point arithmetic.

Precise calculations: For exact-value numbers, calculations do not introduce floating-point errors. Instead, exact precision is used. For example, MySQL treats a number such as .0001 as an exact value rather than as an approximation, and summing it 10,000 times produces a result of exactly 1, not a value that is merely “close” to 1.

Well-defined rounding behavior: For exact-value numbers, the result of ROUND() depends on its argument, not on environmental factors such as how the underlying C library works.

Platform independence: Operations on exact numeric values are the same across different platforms such as Windows and Unix.

Control over handling of invalid values: Overflow and division by zero are detectable and can be treated as errors. For example, you can treat a value that is too large for a column as an error rather than having the value truncated to lie within the range of the column's data type. Similarly, you can treat division by zero as an error rather than as an operation that produces a result of NULL. The choice of which approach to take is determined by the setting of the server SQL mode.