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Interval Data Types
Values of interval data type represent durations of time in year-month units (years and months)
or in day-time units (days, hours, minutes, seconds, and fractions of a second).
interval-type is:
INTERVAL { start-field TO end-field | single-field }
start-field is:
{YEAR | MONTH | DAY | HOUR | MINUTE} [(leading-precision)]
end-field is:
YEAR | MONTH | DAY | HOUR | MINUTE | SECOND
[(fractional-precision)]
single-field is:
start-field | SECOND [(leading-precision,
INTERVAL { start-field TO end-field | single-field }
specifies a column that represents a duration of time as a year-month or day-time range or
a single-field. The optional sign indicates if this is a positive or negative integer. If you omit
the sign, it defaults to positive.
If the interval is specified as a range, the start-field and end-field must be in one of
these categories:
{YEAR | MONTH | DAY | HOUR | MINUTE} [(leading-precision)]
specifies the start-field. A start-field can have a leading-precision up to 18
digits (the maximum depends on the number of fields in the interval). The
leading-precision is the number of digits allowed in the start-field. The default
for leading-precision is 2.
YEAR | MONTH | DAY | HOUR | MINUTE | SECOND [(fractional- precision)]
specifies the end-field. If the end-field is SECOND, it can have a
fractional-precision up to 6 digits. The fractional-precision is the number of
digits of precision after the decimal point. The default for fractional-precision is 6.
start-field | SECOND [(leading-precision, fractional-precision)]
specifies the single-field. If the single-field is SECOND, the leading-precision
is the number of digits of precision before the decimal point, and the
fractional-precision is the number of digits of precision after the decimal point.
The default for leading-precision is 2, and the default for fractional-precision
is 6. The maximum for leading-precision is 18, and the maximum for
fractional-precision is 6.
Considerations for Interval Data Types
Interval Leading Precision
The maximum for the leading-precision depends on the number of fields in the interval
and on the fractional-precision. The maximum is computed as:
max-leading-precision = 18 - fractional-precision - 2 * (N - 1)
where N is the number of fields in the interval.
For example, the maximum number of digits for the leading-precision in a column with
data type INTERVAL YEAR TO MONTH is computed as: 18 – 0 – 2 * (2 – 1) = 16
Interval Ranges
204
SQL Language Elements
fractional-precision)]
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