摘要: dual是一个虚拟表,用来构成select的语法规则,oracle保证dual里面永远只有一条记录。 select sys_guid() from dual 阅读全文
posted @ 2020-03-26 14:11 消失的手套 阅读(276) 评论(0) 推荐(0)
摘要: select count(1) from lims_folderservgrp t2 left join lims_folders t1 on t1.foldersid = t2.foldersid left join lims_clearanceform t on t1.clearanceid = 阅读全文
posted @ 2020-03-26 09:45 消失的手套 阅读(179) 评论(0) 推荐(0)