使用内部连接连接时间戳略有不同的 mySQL 列

Question

我想从两个数据库的不同表中查询，以时间戳为共同特征。目前，我的结果为空集，并带有多个警告。我的查询设计是：

SELECT tableA.ts, tableB.column1, time_to_sec(tableC.column1) as duration, 
tableD.column1 FROM databaseA.tableA \
INNER JOIN databaseB.tableB ON tableA.ts = tableB.ts \
BETWEEN tableA.ts - INTERVAL 50 SECOND AND tableA.ts + INTERVAL 50 SECOND \
INNER JOIN databaseB.tableC ON tableB.ts = tableC.ts \
BETWEEN tableB.ts - INTERVAL 50 SECOND AND tableB.ts + INTERVAL 50 SECOND \
INNER JOIN databaseB.tableD ON tableC.ts = tableD.ts \
BETWEEN tableC.ts - INTERVAL 50 SECOND AND tableC.ts + INTERVAL 50 SECOND \
WHERE TIME(tableA.ts) between '08:59:00' AND '09:01:00'; #getting values at 9am here

TableA来自数据库A。Tables B、C、D来自数据库B。ts指的是时间戳，我是根据common在表之间加入的时间戳。但是，由于时间戳彼此之间略微相差几秒钟，我添加了例如BETWEEN tableB.ts - INTERVAL 50 SECOND AND tableB.ts + INTERVAL 50 SECOND之间INNER JOIN。我认为这可能是导致问题的原因，但是，我不太确定。如果是这样，我该如何修改这个问题？

Answer 1

更好的方法是使用内置函数，例如 ABS 和 TIMESTAMPDIFF:

SELECT tableA.ts, tableB.column1, TIME_TO_SEC(tableC.column1) as duration, tableD.column1 
FROM databaseA.tableA
INNER JOIN databaseB.tableB ON ABS(TIMESTAMPDIFF(SECOND, tableA.ts, tableB.ts)) <= 50
INNER JOIN databaseB.tableC ON ABS(TIMESTAMPDIFF(SECOND, tableB.ts, tableC.ts)) <= 50
INNER JOIN databaseB.tableD ON ABS(TIMESTAMPDIFF(SECOND, tableC.ts, tableD.ts)) <= 50
WHERE TIME(tableA.ts) between '08:59:00' AND '09:01:00';

使用内部连接连接时间戳略有不同的 mySQL 列

Using inner join to join mySQL columns with slightly different timestamps

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sql-optimization

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