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Operators
Arithmetic operators: +, -, *, /, %, DIV, MOD
: The standard arithmetic operators. Arithmetic calculations involving those
can be performed in three different modes: (a) using single-precision,
32-bit IEEE 754 floating point values (the default), (b) using signed 32-bit integers,
(c) using 64-bit signed integers. The expression parser will automatically switch
to integer mode if there are no operations the result in a floating point value.
Otherwise, it will use the default floating point mode. For instance, a+b
will be computed using 32-bit integers if both arguments are 32-bit integers;
or using 64-bit integers if both arguments are integers but one of them is
64-bit; or in floats otherwise. However, a/b or sqrt(a)
will always be computed in floats, because these operations return a result
of non-integer type. To avoid the first, you can either use IDIV(a,b)
or a DIV b form. Also, a*b
will not be automatically promoted to 64-bit when the arguments are 32-bit.
To enforce 64-bit results, you can use BIGINT(). (But note that if there are
non-integer operations, BIGINT() will simply be ignored.)
Comparison operators: <, > <=, >=, =, <>
: Comparison operators (eg. = or <=) return 1.0 when the condition is true and 0.0 otherwise.
For instance, (a=b)+3 will evaluate to 4 when attribute 'a' is equal to attribute 'b', and to 3 when 'a' is not.
Unlike MySQL, the equality comparisons (ie. = and <> operators) introduce a small equality threshold (1e-6 by default).
If the difference between compared values is within the threshold, they will be considered equal.
Boolean operators: AND, OR, NOT : Boolean operators (AND, OR, NOT) were introduced in 0.9.9-rc2 and behave as usual. They are left-associative and have the least priority compared to other operators. NOT has more priority than AND and OR but nevertheless less than any other operator. AND and OR have the same priority so brackets use is recommended to avoid confusion in complex expressions.
Bitwise operators: &, | : These operators perform bitwise AND and OR respectively. The operands must be of an integer types. Introduced in version 1.10-beta.
