摘要：
Drupal 7 has a few security updates, more usability updates and new database features. By default, Drupal 7 has support for MySQL, MariaDB, and SQLite, but now it is possible to do the installation u... 阅读全文
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该图来自:http://kamranagayev.com/2009/08/10/oracle-10gr2-architecture-learn-it-by-heart/ 阅读全文
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操作符：UNION、描述：组合每个查询返回的所有行，并删除重复行SELECT*FROM emp WHERE deptno=10 UNION SELECT*FROM emp WHERE sal>500操作符：UNION ALL、描述：组合每个查询返回的所有行，并包括重复行SELECT*FROM emp WHERE deptno=10 UNION ALL SELECT*FROM emp WHERE s... 阅读全文