目录1. 核心概念：DATEDIFF 究竟在计算什么？2. 主流数据库中的 DATEDIFF 实现2.1 SQL Server：功能强大，但也最易误用2.2 mysql / mariadb：简单直观，但功能有限2.3 PostgreSQL：无2.3 PostgreSQL：无 DATEDIFF，但
I have a very large database with about 120 Million records in one table.I have clean up the data in this table first before I divide it into several tables(possibly normalizing it). The columns of th
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