mysql - Bigquery : search multiple tables and aggregate with first_seen and last_seen

Question

我有一个包含多个表的 Bigquery 数据库:

table1
    id,timestamp,data
    1,1428969600,AAAAA
    2,1428969600,CCCCC
    [..]
    20,1428969600,ZZZZZ

table2
    id,timestamp,data
    1,1429056000,AAAAA
    2,1429056000,BBBBB
    3,1429056000,CCCCC
    [..]
    20,1429056000,ZZZZZ

table3
    id,timestamp,data
    1,1429142400,AAAAA
    2,1429142400,BBBBB
    3,1429142400,CCCCC
    [..]
    20,1429142400,ZZZZZ

我想对所有表(table1、table2 和 table3)进行搜索，以查看“data”字段中的值首次和最后出现的时间，并获取关联的字段“timestamp”。

这应该是结果:

id,timestamp_first, timestamp_last,data
1,1428969600,1429142400,AAAAA
2,1429056000,1429142400,BBBBB
3,1428969600,1429142400,CCCCC
[..]
20,1428969600,1429142400,ZZZZZ

有人可以给我一些提示，如何进行这样的搜索吗？

马丁

Answer 1

我首先会合并表(在 BigQuery 中，合并的语法是逗号)。那么有两种方法:

1. 使用分析函数 FIRST_VALUE 和 LAST_VALUE。

SELECT id, timestamp_first, timestamp_last, data FROM
(SELECT 
  id,
  timestamp,
  FIRST_VALUE(timestamp) OVER(
    PARTITION BY id
    ORDER BY timestamp ASC
    ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING)
  AS timestamp_first,
  LAST_VALUE(timestamp) OVER(
    PARTITION BY id
    ORDER BY timestamp ASC
    ROWS BETWEEN UNBOUNDED PRECEDING AND UNBOUNDED FOLLOWING)
  AS timestamp_last
FROM table1, table2, table3

对时间戳使用聚合 MIN/MAX 来查找第一个/最后一个，然后连接回相同的表。

SELECT a.id id, timestamp_first, timestamp_last, data FROM
(SELECT id, data FROM table1,table2,table3) a
INNER JOIN
(SELECT 
   id, 
   MIN(timestamp) timestamp_first,
   MAX(timestamp) timestamp_last 
 FROM table1,table2,table3 GROUP BY id) b
ON a.id = b.id