# 9.19. Range Functions and Operators

See 8.17절 for an overview of range types.

표 9-49 shows the operators available for range types.

표 9-49. Range Operators

OperatorDescriptionExampleResult
= equalint4range(1,5) = '[1,4]'::int4ranget
<> not equalnumrange(1.1,2.2) <> numrange(1.1,2.3)t
< less thanint4range(1,10) < int4range(2,3)t
> greater thanint4range(1,10) > int4range(1,5)t
<= less than or equalnumrange(1.1,2.2) <= numrange(1.1,2.2)t
>= greater than or equalnumrange(1.1,2.2) >= numrange(1.1,2.0)t
@> contains rangeint4range(2,4) @> int4range(2,3)t
@> contains element'[2011-01-01,2011-03-01)'::tsrange @> '2011-01-10'::timestampt
<@ range is contained byint4range(2,4) <@ int4range(1,7)t
<@ element is contained by42 <@ int4range(1,7)f
&& overlap (have points in common)int8range(3,7) && int8range(4,12)t
<< strictly left ofint8range(1,10) << int8range(100,110)t
>> strictly right ofint8range(50,60) >> int8range(20,30)t
&< does not extend to the right ofint8range(1,20) &< int8range(18,20)t
&> does not extend to the left ofint8range(7,20) &> int8range(5,10)t
-|- is adjacent tonumrange(1.1,2.2) -|- numrange(2.2,3.3)t
+ unionnumrange(5,15) + numrange(10,20)[5,20)
* intersectionint8range(5,15) * int8range(10,20)[10,15)
- differenceint8range(5,15) - int8range(10,20)[5,10)

The simple comparison operators <, >, <=, and >= compare the lower bounds first, and only if those are equal, compare the upper bounds. These comparisons are not usually very useful for ranges, but are provided to allow B-tree indexes to be constructed on ranges.

The left-of/right-of/adjacent operators always return false when an empty range is involved; that is, an empty range is not considered to be either before or after any other range.

The union and difference operators will fail if the resulting range would need to contain two disjoint sub-ranges, as such a range cannot be represented.

표 9-50 shows the functions available for use with range types.

표 9-50. Range Functions

FunctionReturn TypeDescriptionExampleResult
`lower`(anyrange) range's element typelower bound of rangelower(numrange(1.1,2.2))1.1
`upper`(anyrange) range's element typeupper bound of rangeupper(numrange(1.1,2.2))2.2
`isempty`(anyrange) booleanis the range empty?isempty(numrange(1.1,2.2))false
`lower_inc`(anyrange) booleanis the lower bound inclusive?lower_inc(numrange(1.1,2.2))true
`upper_inc`(anyrange) booleanis the upper bound inclusive?upper_inc(numrange(1.1,2.2))false
`lower_inf`(anyrange) booleanis the lower bound infinite?lower_inf('(,)'::daterange)true
`upper_inf`(anyrange) booleanis the upper bound infinite?upper_inf('(,)'::daterange)true
`range_merge`(anyrange, anyrange) anyrangethe smallest range which includes both of the given rangesrange_merge('[1,2)'::int4range, '[3,4)'::int4range)[1,4)

The `lower` and `upper` functions return null if the range is empty or the requested bound is infinite. The `lower_inc`, `upper_inc`, `lower_inf`, and `upper_inf` functions all return false for an empty range.