时态数据库(temporal database) 在 oracle 中的实现
时态数据库是种以时间为基础的数据库，它所实现的不仅仅是对当前数据库的处理，也可以对过去和未来进行处理。
A temporal database is a database with built-in time aspects, e.g. a temporal data model and a temporal version of structured query language.
1. 在oracle 中创建 Type
CREATE TYPE PeriodType AS OBJECT ( ------------------------------------------- -- Section 1: Member variables ------------------------------------------- -- Note1: This is a close-open period. -- Note2: This code is for Oracle m_start DATE, -- start of the period m_end DATE, -- end of the period . . . )
2.上面的省略号中要插入member function.
---------------------------------------------------------------------------
-- Section 2: Member functions to get the attribute of this object
---------------------------------------------------------------------------
-- 2.1 public function: Get the length of this period.
--return -2 if this period is end-with-forever
--return -1 if this period is invalid
MEMBER FUNCTION PeriodLength RETURN NUMBER,
-- 2.2 public function: Check if the date is end with forever.
--return 1 for TRUE, 0 for FALSE, -1 if this period is invalid
MEMBER FUNCTION IsEndWithForever RETURN INTEGER,
-- 2.3 private function: Check if the period is a valid period, that is m_end > m_begin.
--return 1 for valid, o for invalid.
MEMBER FUNCTION IsValid RETURN INTEGER,
---------------------------------------------------------------------------
-- Section 3: Member functions to get the relationship with an instant point.
---------------------------------------------------------------------------
-- 3.1 public function: Check if the date is in this period.
--return 1 for TRUE, 0 for FALSE, -1 if this period is invalid
--Note: if the date is the end of the period, it is not in this period,
--because this is a close-open period.
MEMBER FUNCTION IsDateIn(d DATE) RETURN INTEGER,
-- 3.2 public function: Check if the date is out of this period.
--return 1 for TRUE, 0 for FALSE, -1 if this period is invalid
--Note: if the date is the end of the period, it is outside of the period,
--because this is a close-open period.
MEMBER FUNCTION IsDateOut(d DATE) RETURN INTEGER,
-- 3.3 public function: Check if the date is same to the start point of this period.
--return 1 for TRUE, 0 for FALSE, -1 if this period is invalid
MEMBER FUNCTION IsDateStart(d DATE) RETURN INTEGER,
-- 3.4 public function: Check if the date is same to the end point of this period.
--return 1 for TRUE, 0 for FALSE, -1 if this period is invalid
MEMBER FUNCTION IsDateEnd(d DATE) RETURN INTEGER,
-- 3.5 public function: Check if the date is eailier than this period.
--return 1 for TRUE, 0 for FALSE, -1 if this period is invalid
MEMBER FUNCTION IsDateBeforeStart(d DATE) RETURN INTEGER,
-- 3.6 public function: Check if the date is later than this period.
--return 1 for TRUE, 0 for FALSE, -1 if this period is invalid
MEMBER FUNCTION IsDateAfterEnd(d DATE) RETURN INTEGER,
-- 3.7 public function: Get the interval between the date and the start of this period.
--return 1 for TRUE, 0 for FALSE, -1 if this period is invalid
MEMBER FUNCTION DistanceToBegin(d DATE) RETURN NUMBER,
-- 3.8 public function: Get the interval between the date and the end of this period.
--return 1 for TRUE, 0 for FALSE, -1 if this period is invalid
--Note: if either the date or the end of this period is MAX_TIME, this function returns -2
MEMBER FUNCTION DistanceToEnd(d DATE) RETURN NUMBER,
-- 3.9 public function: Get the minimal interval between the date and the points in this period.
MEMBER FUNCTION DistanceToWholePeriod(d DATE) RETURN NUMBER,
---------------------------------------------------------------------------
-- Section 4: Member functions to get the relationship with an other period.
---------------------------------------------------------------------------
-- 4.1 public function: check if the period is disjoint with this period, with a gap bigger than zero.
--return 1 for TRUE, 0 for FALSE, -1 if either this period or input period is invalid
MEMBER FUNCTION IsDisjointWithGap(p PeriodType) RETURN INTEGER,
-- 4.2 public function: check if the period is disjoint with this period, without a gap.
--return 1 for TRUE, 0 for FALSE, -1 if either this period or input period is invalid
MEMBER FUNCTION IsDisjointWithoutGap(p PeriodType) RETURN INTEGER,
-- 4.3 public function: check if the period is disjoint with this period.
--return 1 for TRUE, 0 for FALSE, -1 if either this period or input period is invalid
MEMBER FUNCTION IsDisjoint(p PeriodType) RETURN INTEGER,
-- 4.4 public function: Get the gap getween the period and this period
MEMBER FUNCTION GapLength(p PeriodType) RETURN NUMBER,
-- 4.5 public function: check if the period is same with this period.
--return 1 for TRUE, 0 for FALSE, -1 if either this period or input period is invalid
MEMBER FUNCTION IsEqual(p PeriodType) RETURN INTEGER,
-- 4.6 public function: check if this period covers the period.
--return 1 for TRUE, 0 for FALSE, -1 if either this period or input period is invalid
MEMBER FUNCTION IsCover(p PeriodType) RETURN INTEGER,
-- 4.7 public function: check if this period is covered by the period.
--return 1 for TRUE, 0 for FALSE, -1 if either this period or input period is invalid
MEMBER FUNCTION IsCovered(p PeriodType) RETURN INTEGER,
-- 4.8 public function: check if the period is overlap with this period.
--return 1 for TRUE, 0 for FALSE, -1 if either this period or input period is invalid
MEMBER FUNCTION IsOverlap(p PeriodType) RETURN INTEGER,
-- 4.9 public function: check if the period intersects with this period.
--return 1 for TRUE, 0 for FALSE, -1 if either this period or input period is invalid
MEMBER FUNCTION IsIntersect(p PeriodType) RETURN INTEGER,
-- 4.10 public function: Get the intersect length of the period and this period
--NOTE: if both periods are end-with-forever, the function returns -1;
MEMBER FUNCTION IntersectLength(p PeriodType) RETURN NUMBER,
-- 4.11 public constructor: Get the intersect period of the period and this period
MEMBER FUNCTION IntercectPeriod(p PeriodType) RETURN PeriodType
3. 创建 global function
-- 5.1 private function: Check if the date is the max date time.
CREATE OR REPLACE FUNCTION IsMaxDateTime(d Date) RETURN INTEGER IS
BEGIN
IF TRUNC(d) = Date '9999-12-31' THEN
RETURN 1;
ELSE
RETURN 0;
END IF;
END;
/
show errors
-- 5.2 private function: compare 2 dates. returns 1 if d1 > d2; returns 0 if d1 = d2; returns -1 if d1 < d2;
CREATE OR REPLACE FUNCTION CompareDates(d1 Date, d2 Date) RETURN INTEGER IS
BEGIN
IF IsMaxDateTime(d1) = 1 OR IsMaxDateTime(d2) = 1 THEN
IF TRUNC(d1) > TRUNC(d2) THEN
RETURN 1;
ELSIF TRUNC(d1) = TRUNC(d2) THEN
RETURN 0;
ELSE
RETURN -1;
END IF;
ELSE
IF d1 > d2 THEN
RETURN 1;
ELSIF d1 = d2 THEN
RETURN 0;
ELSE
RETURN -1;
END IF;
END IF;
END;
/
show errors
CREATE OR REPLACE FUNCTION LengthBetweenDates(d1 Date, d2 Date) RETURN INTEGER IS
BEGIN
IF IsMaxDateTime(d1) = 1 THEN
RETURN -2;
ELSIF IsMaxDateTime(d2) = 1 THEN
RETURN -2;
ELSE
IF d1 > d2 THEN
RETURN d1-d2;
ELSE
RETURN d2-d1;
END IF;
END IF;
END;
/
show errors
CREATE OR REPLACE FUNCTION MakePeriodFromStartEnd(d1 Date, d2 Date) RETURN PeriodType IS
BEGIN
IF CompareDates(d1, d2) = -1 THEN
RETURN PeriodType(d1, d2);
ELSE
RETURN PeriodType(d2, d1);
END IF;
END;
/
show errors
CREATE OR REPLACE FUNCTION MakePeriodFromStartLength(d_start Date, n_len NUMBER ) RETURN PeriodType IS
BEGIN
RETURN MakePeriodFromStartEnd(d_start, d_start+n_len);
END;
/
show errors
4. 要实现这些member function
CREATE OR REPLACE TYPE BODY PeriodType AS
MEMBER FUNCTION IsValid RETURN INTEGER IS
BEGIN
IF IsMaxDateTime(m_start) = 1 THEN
RETURN 0;
END IF;
IF m_end <= m_start THEN
RETURN 0;
END IF;
RETURN 1;
END;
MEMBER FUNCTION PeriodLength RETURN NUMBER IS
BEGIN
IF IsValid() = 0 THEN
RETURN -1;
END IF;
RETURN LengthBetweenDates(m_end, m_start);
END;
MEMBER FUNCTION IsEndWithForever RETURN INTEGER IS
BEGIN
IF IsValid() = 0 THEN
RETURN -1;
END IF;
RETURN IsMaxDateTime(m_end);
END;
MEMBER FUNCTION IsDateIn(d DATE) RETURN INTEGER IS
BEGIN
IF IsValid() = 0 THEN
RETURN -1;
END IF;
--if m_start > d, return false;
IF m_start > d THEN
RETURN 0;
END IF;
--if m_end < d, return false;
IF CompareDates(m_end, d) = -1 THEN
RETURN 0;
END IF;
--if m_end = d, return false;
IF CompareDates(m_end, d) = 0 THEN
RETURN 0;
END IF;
RETURN 1;
END;
MEMBER FUNCTION IsDateOut(d DATE) RETURN INTEGER IS
BEGIN
IF IsValid() = 0 THEN
RETURN -1;
END IF;
IF IsDateIn(d) = 1 THEN
RETURN 0;
ELSE
RETURN 1;
END IF;
END;
MEMBER FUNCTION IsDateStart(d DATE) RETURN INTEGER IS
BEGIN
IF IsValid() = 0 THEN
RETURN -1;
END IF;
IF m_start = d THEN
RETURN 1;
ELSE
RETURN 0;
END IF;
END;
MEMBER FUNCTION IsDateEnd(d DATE) RETURN INTEGER IS
BEGIN
IF IsValid() = 0 THEN
RETURN -1;
END IF;
IF CompareDates(m_end, d) = 0 THEN
RETURN 1;
ELSE
RETURN 0;
END IF;
END;
MEMBER FUNCTION IsDateBeforeStart(d DATE) RETURN INTEGER IS
BEGIN
IF IsValid() = 0 THEN
RETURN -1;
END IF;
IF m_start > d THEN
RETURN 1;
ELSE
RETURN 0;
END IF;
END;
MEMBER FUNCTION IsDateAfterEnd(d DATE) RETURN INTEGER IS
BEGIN
IF IsValid() = 0 THEN
RETURN -1;
END IF;
IF CompareDates(m_end, d) = -1 THEN
RETURN 1;
ELSE
RETURN 0;
END IF;
END;
MEMBER FUNCTION DistanceToBegin(d DATE) RETURN NUMBER IS
BEGIN
IF IsValid() = 0 THEN
RETURN -1;
END IF;
RETURN LengthBetweenDates(m_start, d);
END;
MEMBER FUNCTION DistanceToEnd(d DATE) RETURN NUMBER IS
BEGIN
IF IsValid() = 0 THEN
RETURN -1;
END IF;
RETURN LengthBetweenDates(m_end, d);
END;
MEMBER FUNCTION DistanceToWholePeriod(d DATE) RETURN NUMBER IS
BEGIN
IF IsValid() = 0 THEN
RETURN -1;
END IF;
IF IsDateIn(d) = 1 THEN
RETURN 0;
END IF;
IF IsDateEnd(d) = 1 THEN
RETURN 0;
END IF;
IF IsDateBeforeStart(d) = 1 THEN
RETURN LengthBetweenDates(m_start, d);
END IF;
RETURN LengthBetweenDates(m_end, d);
END;
MEMBER FUNCTION IsDisjointWithGap(p PeriodType) RETURN INTEGER IS
BEGIN
IF IsValid() = 0 THEN
RETURN -1;
END IF;
IF p.IsValid() = 0 THEN
RETURN -1;
END IF;
IF m_end < p.m_start THEN
RETURN 1;
ELSIF p.m_end < m_start THEN
RETURN 1;
ELSE
RETURN 0;
END IF;
END;
MEMBER FUNCTION IsDisjointWithoutGap(p PeriodType) RETURN INTEGER IS
BEGIN
IF IsValid() = 0 THEN
RETURN -1;
END IF;
IF p.IsValid() = 0 THEN
RETURN -1;
END IF;
IF m_end = p.m_start THEN
RETURN 1;
ELSIF p.m_end = m_start THEN
RETURN 1;
ELSE
RETURN 0;
END IF;
END;
MEMBER FUNCTION IsDisjoint(p PeriodType) RETURN INTEGER IS
BEGIN
IF IsValid() = 0 THEN
RETURN -1;
END IF;
IF p.IsValid() = 0 THEN
RETURN -1;
END IF;
IF IsDisjointWithGap(p) = 1 THEN
RETURN 1;
ELSIF IsDisjointWithoutGap(p) = 1 THEN
RETURN 1;
ELSE
RETURN 0;
END IF;
END;
MEMBER FUNCTION GapLength(p PeriodType) RETURN NUMBER IS
BEGIN
IF IsValid() = 0 THEN
RETURN -1;
END IF;
IF p.IsValid() = 0 THEN
RETURN -1;
END IF;
IF IsDisjointWithGap(p) = 0 THEN
RETURN 0;
ELSE
IF m_start > p.m_end THEN
RETURN m_start - p.m_end;
ELSE
RETURN p.m_start - m_end;
END IF;
END IF;
END;
MEMBER FUNCTION IsCover(p PeriodType) RETURN INTEGER IS
BEGIN
IF IsValid() = 0 THEN
RETURN -1;
END IF;
IF p.IsValid() = 0 THEN
RETURN -1;
END IF;
IF m_start <= p.m_start THEN
IF CompareDates(m_end, p.m_end)=0 THEN
RETURN 1;
ELSIF CompareDates(m_end, p.m_end)=1 THEN
RETURN 1;
ELSE
RETURN 0;
END IF;
ELSE
RETURN 0;
END IF;
END;
MEMBER FUNCTION IsCovered(p PeriodType) RETURN INTEGER IS
BEGIN
IF IsValid() = 0 THEN
RETURN -1;
END IF;
IF p.IsValid() = 0 THEN
RETURN -1;
END IF;
IF p.IsCover(MakePeriodFromStartEnd(m_start, m_end)) = 1 THEN
RETURN 1;
ELSE
RETURN 0;
END IF;
END;
MEMBER FUNCTION IsEqual(p PeriodType) RETURN INTEGER IS
BEGIN
IF IsValid() = 0 THEN
RETURN -1;
END IF;
IF p.IsValid() = 0 THEN
RETURN -1;
END IF;
IF IsCover(p) = 1 AND IsCovered(p) = 1 THEN
RETURN 1;
ELSE
RETURN 0;
END IF;
END;
MEMBER FUNCTION IsOverlap(p PeriodType) RETURN INTEGER IS
BEGIN
IF IsValid() = 0 THEN
RETURN -1;
END IF;
IF p.IsValid() = 0 THEN
RETURN -1;
END IF;
IF m_start < p.m_end AND p.m_start < m_end THEN
RETURN 1;
ELSE
RETURN 0;
END IF;
END;
MEMBER FUNCTION IsIntersect(p PeriodType) RETURN INTEGER IS
BEGIN
IF IsValid() = 0 THEN
RETURN -1;
END IF;
IF p.IsValid() = 0 THEN
RETURN -1;
END IF;
IF IsDisjoint(p) = 0 THEN
RETURN 1;
ELSE
RETURN 0;
END IF;
END;
MEMBER FUNCTION IntercectPeriod(p PeriodType) RETURN PeriodType IS
BEGIN
IF IsIntersect(p) = 0 THEN
RETURN PeriodType(Date '9999-12-31', Date '9999-12-31');
ELSE
IF IsCover(p) = 1 THEN
RETURN p;
ELSIF IsCovered(p) = 1 THEN
RETURN PeriodType(m_start, m_end);
ELSE
IF m_start < p.m_start THEN
RETURN PeriodType(p.m_start, m_end);
ELSE
RETURN PeriodType(m_start, p.m_end);
END IF;
END IF;
END IF;
RETURN p;
END;
MEMBER FUNCTION IntersectLength(p PeriodType) RETURN NUMBER IS
BEGIN
IF IsValid() = 0 THEN
RETURN -1;
END IF;
IF p.IsValid() = 0 THEN
RETURN -1;
END IF;
RETURN IntercectPeriod(p).PeriodLength();
END;
END;
/