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An aggregate function that returns the first value of a set of input values, defined as the value associated with the minimum time.
FIRST (value[, time]);
- value: column value to return
- time: time expression for comparison. The expression should be one of the following types:
TIMESTAMP(6). If no time expression is specified, then the
SERIES TIMESTAMPis used to defined the time order. Only one
SERIES TIMESTAMPcan appear in tables used in the query if the
timeargument is omitted.
The first value of a set of input rows, as ordered by the time column.
- If there are multiple instances of the same minimum time expression, then this function returns an arbitrary value from among the values corresponding with that minimum.
- The function returns an error if there are multiple
SERIES TIMESTAMPcolumns involved, or one is needed due to omission of the
timeargument but none is present. For example, if more than one table in the
FROMclause has a
SERIES TIMESTAMP, then it becomes ambiguous which timestamp to use. Hence, the
SERIES TIMESTAMPto be used must be specified in the second argument of the
The following examples display the use of
CREATE TABLE table1 (a INT, b DATETIME SERIES TIMESTAMP);
INSERT INTO table1 values (1, "2019-03-14 06:28:00"), (2, "2019-04-14 06:28:00"), (3, "2018-03-14 06:28:00");
SELECT FIRST (a) FROM table1; +--------------+ | FIRST (a) | +--------------+ | 3 | +--------------+
SELECT FIRST (a, b) FROM table1; **** +--------------+ | FIRST (a, b) | +--------------+ | 3 | +--------------+