问:有一个postgres数据表,表中有update_time, create_time关于时间戳的字段,选择某个时间段,计算出update_time减去create_time的值做为耗时时间的字段duration_time,统计出在这段时间内耗时时间的平均值,中位数值,最大值,和最小值,请问如何通过sql语句实现此统计?
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答:您好!您可以使用以下SQL语句来实现您所描述的统计:
SELECT AVG(duration_time) AS avg_duration, PERCENTILE_CONT(0.5) WITHIN GROUP (ORDER BY duration_time) AS median_duration, MAX(duration_time) AS max_duration, MIN(duration_time) AS min_duration FROM ( SELECT update_time - create_time AS duration_time FROM your_table_name WHERE update_time BETWEEN start_time AND end_time ) subquery;
请注意,您需要将
your_table_name
替换为您的表名,start_time
和end_time
替换为您想要查询的时间段。希望这对您有帮助!
表中还有另一个字段处置策略字段为handle_strategy, 按照handle_strategy分组 统计,如何改写上面的查询?
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您好!如果您想按照
handle_strategy
字段分组统计,可以使用以下SQL语句:SELECT handle_strategy, AVG(duration_time) AS avg_duration, PERCENTILE_CONT(0.5) WITHIN GROUP (ORDER BY duration_time) AS median_duration, MAX(duration_time) AS max_duration, MIN(duration_time) AS min_duration FROM ( SELECT handle_strategy, update_time - create_time AS duration_time FROM your_table_name WHERE update_time BETWEEN start_time AND end_time ) subquery GROUP BY handle_strategy;
请注意,您需要将
your_table_name
替换为您的表名,start_time
和end_time
替换为您想要查询的时间段。希望这对您有帮助!
平均数统计保留到整数位,不需要小数; 上面PERCENTILE_CONT(0.5) WITHIN GROUP语句表示的是什么意思?
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您好!如果您想将平均数统计保留到整数位,可以使用
ROUND
函数来实现。以下是修改后的SQL语句:SELECT handle_strategy, ROUND(AVG(duration_time)) AS avg_duration, PERCENTILE_CONT(0.5) WITHIN GROUP (ORDER BY duration_time) AS median_duration, MAX(duration_time) AS max_duration, MIN(duration_time) AS min_duration FROM ( SELECT handle_strategy, update_time - create_time AS duration_time FROM your_table_name WHERE update_time BETWEEN start_time AND end_time ) subquery GROUP BY handle_strategy;
至于您问的
PERCENTILE_CONT(0.5) WITHIN GROUP (ORDER BY duration_time)
语句,它表示计算duration_time
字段的中位数。PERCENTILE_CONT
是一个聚合函数,它用于计算连续分布的给定百分位数。在这里,我们使用0.5
作为参数,表示我们想要计算中位数(即第50百分位数)。WITHIN GROUP (ORDER BY duration_time)
子句用于指定对哪个字段进行排序以计算百分位数。文章来源:https://www.toymoban.com/news/detail-630143.html希望这些信息对您有帮助!文章来源地址https://www.toymoban.com/news/detail-630143.html
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