mysql - 从 2 个表中选择条件

Question

我需要一个 SQL 查询，用于从 2 个表中选择多个条件。

table1
order_row | timestamp |
-----------------------
0001      |2016-11-04 |
0002      |2016-11-04 |
0003      |2016-11-04 |
0004      |2016-11-03 |
0006      |2016-11-03 |

table2
order_row | timestamp |
-----------------------
0001      |2016-11-05 |
0002      |2016-11-04 |
0003      |2016-11-04 |
0004      |2016-11-04 |
0005      |2016-11-04 |
0006      |2016-11-02 |

我想获取所有行，以便从 table2 获取所有 order_row 行，这些行不存在于 table1 和 order_row 来自 table2 的行，其时间戳在 table2 中比 table1 更新。并且仅检查 表 2 中 timestamp 比 2016-11-03 更新的行。
结果必须是:

order_row | 
----------
0001      | because timestamp is newer in table2
0004      | because timestamp is newer in table2
0005      | because it's not present in table1

Answer 1

应该这样做:

SELECT t2.*
FROM Table2 AS t2
LEFT JOIN Table1 AS t1 
   ON t2.order_row = t1.order_row 
WHERE t1.order_row IS NULL OR t2.`timestamp` > t1.`timestamp` 

Demo here

编辑:如果您只想考虑 table2 中比 '2016-11-03' 更新的记录，则只需添加:

t2.`timestamp` > '2016-11-03' AND ( ... other conditions here ...)