9.20. 範圍函式及運算子
Table 9.53 shows the specialized operators available for range types. In addition to those, the usual comparison operators shown in Table 9.1 are available for range types. The comparison operators order first by the range lower bounds, and only if those are equal do they compare the upper bounds. This does not usually result in a useful overall ordering, but the operators are provided to allow unique indexes to be constructed on ranges.
Operator Description Example(s) |
anyrange @> anyrange → booleanDoes the first range contain the second? int4range(2,4) @> int4range(2,3) → t |
anyrange @> anyelement → booleanDoes the range contain the element? '[2011-01-01,2011-03-01)'::tsrange @> '2011-01-10'::timestamp → t |
anyrange <@ anyrange → booleanIs the first range contained by the second? int4range(2,4) <@ int4range(1,7) → t |
anyelement <@ anyrange → booleanIs the element contained in the range? 42 <@ int4range(1,7) → f |
anyrange && anyrange → booleanDo the ranges overlap, that is, have any elements in common? int8range(3,7) && int8range(4,12) → t |
anyrange << anyrange → booleanIs the first range strictly left of the second? int8range(1,10) << int8range(100,110) → t |
anyrange >> anyrange → booleanIs the first range strictly right of the second? int8range(50,60) >> int8range(20,30) → t |
anyrange &< anyrange → booleanDoes the first range not extend to the right of the second? int8range(1,20) &< int8range(18,20) → t |
anyrange &> anyrange → booleanDoes the first range not extend to the left of the second? int8range(7,20) &> int8range(5,10) → t |
anyrange - |
anyrange + anyrange → anyrangeComputes the union of the ranges. The ranges must overlap or be adjacent, so that the union is a single range (but see range_merge()).numrange(5,15) + numrange(10,20) → [5,20) |
anyrange * anyrange → anyrangeComputes the intersection of the ranges. int8range(5,15) * int8range(10,20) → [10,15) |
anyrange - anyrange → anyrangeComputes the difference of the ranges. The second range must not be contained in the first in such a way that the difference would not be a single range. int8range(5,15) - int8range(10,20) → [5,10) |
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.
Function Description Example(s) |
lower ( anyrange ) → anyelementExtracts the lower bound of the range ( NULL if the range is empty or the lower bound is infinite).lower(numrange(1.1,2.2)) → 1.1 |
upper ( anyrange ) → anyelementExtracts the upper bound of the range ( NULL if the range is empty or the upper bound is infinite).upper(numrange(1.1,2.2)) → 2.2 |
isempty ( anyrange ) → booleanIs the range empty? isempty(numrange(1.1,2.2)) → f |
lower_inc ( anyrange ) → booleanIs the range's lower bound inclusive? lower_inc(numrange(1.1,2.2)) → t |
upper_inc ( anyrange ) → booleanIs the range's upper bound inclusive? upper_inc(numrange(1.1,2.2)) → f |
lower_inf ( anyrange ) → booleanIs the range's lower bound infinite? lower_inf('(,)'::daterange) → t |
upper_inf ( anyrange ) → booleanIs the range's upper bound infinite? upper_inf('(,)'::daterange) → t |
range_merge ( anyrange, anyrange ) → anyrangeComputes the smallest range that includes both of the given ranges. range_merge('[1,2)'::int4range, '[3,4)'::int4range) → [1,4) |
The
lower_inc, upper_inc, lower_inf, and upper_inf functions all return false for an empty range.