[英]postgres: dynamic conditional in function query
我有一个Postgres函数,如果将它传递给函数,我需要动态添加一个条件参数。 功能如下:
CREATE OR REPLACE FUNCTION public.get_appointments(
for_business_id INTEGER,
range_start DATE,
range_end DATE,
for_staff_id INTEGER
)
RETURNS SETOF appointment
LANGUAGE plpgsql STABLE
AS $function$
DECLARE
appointment appointment;
recurrence TIMESTAMP;
appointment_length INTERVAL;
parent_id UUID;
BEGIN
FOR appointment IN
-- NEED TO CONDITIONALLY ADD "WHERE staff_id = for_staff_id"
-- if for_staff_id is NOT NULL
SELECT *
FROM appointment
WHERE business_id = for_business_id
AND (
recurrence_pattern IS NOT NULL
OR (
recurrence_pattern IS NULL
AND starts_at BETWEEN range_start AND range_end
)
)
LOOP
IF appointment.recurrence_pattern IS NULL THEN
RETURN NEXT appointment;
CONTINUE;
END IF;
appointment_length := appointment.ends_at - appointment.starts_at;
parent_id := appointment.id;
FOR recurrence IN
SELECT *
FROM generate_recurrences(
appointment.recurrence_pattern,
appointment.starts_at,
range_start,
range_end
)
LOOP
EXIT WHEN recurrence::date > range_end;
CONTINUE WHEN (recurrence::date < range_start AND recurrence::date > range_end) OR recurrence = ANY(appointment.recurrence_exceptions);
appointment.id := uuid_generate_v5(uuid_nil(), parent_id::varchar || recurrence::varchar);
appointment.parent_id := parent_id;
appointment.starts_at := recurrence;
appointment.ends_at := recurrence + appointment_length;
appointment.recurrence_pattern := appointment.recurrence_pattern;
appointment.recurrence_exceptions := NULL;
appointment.is_recurrence := true;
RETURN NEXT appointment;
END LOOP;
END LOOP;
RETURN;
END;
$function$;
如果将for_staff_id
传递到函数中,则需要将它作为条件( WHERE staff_id = for_staff_id
)添加到位于FOR...IN
循环中的查询中。 我尝试在FOR...IN
执行IF/ELSE
,但出现语法错误。
有一个更好的方法吗?
谢谢!
请注意,我正在运行Postgres 9.5。
只需添加以下内容
... AND (for_staff_id IS NULL OR staff_id = for_staff_id)
或这个
... AND coalesce(staff_id = for_staff_id, true)
在SELECT
语句的WHERE
子句中。
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