TemporalData - Temporal Data Temporal Data Concepts User...

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Temporal Data
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Temporal Data Concepts User Defined Time Instant Interval Period Valid Time Transaction Time
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Instants An anchored location or point on a timeline A datetime is an Instant in SQL Generally 3 specific forms Date, Time, Timestamp Differ by the fields they contain - Year, Month, Day, Hour, Minute, Second Timezone variants Time and Timestamp
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Intervals An unanchored, directional duration of the timeline Contiguous and unanchored Relative measure of time - An Instant is Absolute Interval is a “complex type” Year-month intervals - Integral number of years or months Day-time intervals - Integral number of days, hours, minutes, seconds, or fractions of a second
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Granules Individual units are Granules Years, Months, Days, Hours, …, Microseconds Represents a signed integer number of granules Combinations of the fields Year, month, day, hour, minute, second Not all combinations are allowed Required “leading” field, optional “trailing” field, optional “precision”
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Year-Month Interval Year(p) Interval Month(p) Interval Year(p) to Month Defaults to 2 digits Examples Interval '4' Year - 4 years Interval '7' Month - 7 months Interval '4-7' Year to Month - 4 years and 7 months
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Day-Time Contain day, hour, minute, and second fields Up to 4 fields, one of each Precision specifiers as well Interval Day(4) to Hour - Up to 9999 days and 24 hours
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Time Predicates Equality =, = any, = some, in, match Less Than All others defined in terms of '<' - <, <=, >, >=, <> (or not equal) - between Is Null Overlaps (pf1) overlaps (pf2) pfx is of the form (start time, end time) or (start time, duration)
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TemporalData - Temporal Data Temporal Data Concepts User...

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