要在PostgreSQL中提取datetime的部分字段，可以使用內置的date_part函數。以下是一些常用的示例：
SELECT date_part('year', your_datetime_column) AS year FROM your_table;
SELECT date_part('month', your_datetime_column) AS month FROM your_table;
SELECT date_part('day', your_datetime_column) AS day FROM your_table;
SELECT date_part('hour', your_datetime_column) AS hour FROM your_table;
SELECT date_part('minute', your_datetime_column) AS minute FROM your_table;
SELECT date_part('second', your_datetime_column) AS second FROM your_table;
請注意，your_datetime_column應該替換為您實際的datetime字段，your_table應該替換為您實際的表名。您還可以根據需要自定義日期時間字段的提取方式。
