SQL(MySQL)查询以提取多个时间范围内的聚合
作者:互联网
假设我有下表my_table:
+----------+------------+------------+
+ key_code + cost_value + cost_date +
+----------+------------+------------+
+ AAAA + 1.01 + 2015-01-05 +
+ AAAA + 4.04 + 2015-01-10 +
+ AAAA + 3.03 + 2015-01-15 +
+ AAAA + 2.02 + 2015-01-20 +
+ BBBB + 5.05 + 2015-01-05 +
+ BBBB + 8.08 + 2015-01-10 +
+ BBBB + 7.07 + 2015-01-15 +
+ BBBB + 6.06 + 2015-01-20 +
+----------+------------+------------+
我可以使用以下查询为每个key_code提取最小和最大cost_values:
SELECT key_code, MIN(cost_value) AS cost_min, MAX(cost_value) AS cost_max
FROM my_table
GROUP BY key_code
ORDER BY key_code;
+----------+----------+----------+
+ key_code + cost_min + cost_max +
+----------+----------+----------+
+ AAAA + 1.01 + 4.04 +
+ BBBB + 5.05 + 8.08 +
+----------+----------+----------+
我可以使用以下查询将最近7天(假设今天= 2015-01-21)的最小值/最大值限制为cost_values:
SELECT key_code, MIN(cost_value) AS cost_min_07, MAX(cost_value) AS cost_max_07
FROM my_table
WHERE cost_date >= (CURDATE() - INTERVAL 7 DAY)
GROUP BY key_code
ORDER BY key_code;
+----------+-------------+-------------+
+ key_code + cost_min_07 + cost_max_07 +
+----------+-------------+-------------+
+ AAAA + 2.02 + 3.03 +
+ BBBB + 6.06 + 7.07 +
+----------+-------------+-------------+
但是,如果我想同时提取前7天,14天和21天的最小值/最大值怎么办?我如何(最有效地)产生以下结果?我猜我在问如何对每个MIN()和MAX()对应用不同的WHERE?
+----------+-------------+-------------+-------------+-------------+-------------+-------------+
+ key_code + cost_min_07 + cost_max_07 + cost_min_14 + cost_max_14 + cost_min_21 + cost_max_21 +
+----------+-------------+-------------+-------------+-------------+-------------+-------------+
+ AAAA + 2.02 + 3.03 + 2.02 + 4.04 + 1.01 + 4.04 +
+ BBBB + 6.06 + 7.07 + 6.06 + 8.08 + 5.05 + 8.08 +
+----------+-------------+-------------+-------------+-------------+-------------+-------------+
解决方法:
使用条件聚合:
SELECT key_code,
MIN(CASE WHEN cost_date >= CURDATE() - INTERVAL 7 DAY THEN cost_value END) AS cost_min_07,
MAX(CASE WHEN cost_date >= CURDATE() - INTERVAL 7 DAY THEN cost_value END) AS cost_max_07,
MIN(CASE WHEN cost_date >= CURDATE() - INTERVAL 14 DAY THEN cost_value END) AS cost_min_14,
MAX(CASE WHEN cost_date >= CURDATE() - INTERVAL 14 DAY THEN cost_value END) AS cost_max_14,
MIN(CASE WHEN cost_date >= CURDATE() - INTERVAL 21 DAY THEN cost_value END) AS cost_min_21,
MAX(CASE WHEN cost_date >= CURDATE() - INTERVAL 21 DAY THEN cost_value END) AS cost_max_21
FROM my_table
WHERE cost_date >= (CURDATE() - INTERVAL 21 DAY)
GROUP BY key_code
ORDER BY key_code;
标签:aggregate-functions,sql,mysql 来源: https://codeday.me/bug/20191119/2033512.html