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12.25.1 Types of Numeric Values
The scope of precision math for exact-value operations includes
the exact-value data types (integer and
DECIMAL
types) and exact-value
numeric literals. Approximate-value data types and numeric
literals are handled as floating-point numbers.
Exact-value numeric literals have an integer part or fractional
part, or both. They may be signed. Examples: 1
,
.2
, 3.4
,
-5
, -6.78
,
+9.10
.
Approximate-value numeric literals are represented in scientific
notation with a mantissa and exponent. Either or both parts may be
signed. Examples: 1.2E3
,
1.2E-3
, -1.2E3
,
-1.2E-3
.
Two numbers that look similar may be treated differently. For
example, 2.34
is an exact-value (fixed-point)
number, whereas 2.34E0
is an approximate-value
(floating-point) number.
The DECIMAL
data type is a
fixed-point type and calculations are exact. In MySQL, the
DECIMAL
type has several synonyms:
NUMERIC
,
DEC
,
FIXED
. The integer types also are
exact-value types.
The FLOAT
and
DOUBLE
data types are
floating-point types and calculations are approximate. In MySQL,
types that are synonymous with
FLOAT
or
DOUBLE
are
DOUBLE PRECISION
and
REAL
.
Document created the 26/06/2006, last modified the 26/10/2018
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