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Chapter 5 : NULL 值的处理、逻辑操作和函数嵌套 select e.ename, e.job, e.sal, e.comm from emp e where e.job in ('CLERK','SALESMAN') order by e.job NULL:"unavailable,unassigned,undefined,unknow,immeasurable,inapplica... 阅读全文
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SELECT LOWER('SQL: Structural Query Language')from dual;//dual 是一个虚表(伪表)。UPPER(列名|表达式)SELECT UPPER('sql is used exclusively in rdbmses')from dual;SELECT INITCAP('sql is an ENGLISH LIKE language')from ... 阅读全文
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winver---------检查Windows版本 wmimgmt.msc----打开windows管理体系结构(WMI) wupdmgr--------windows更新程序 wscript--------windows脚本宿主设置 write----------写字板 winmsd---------系统信息 wiaacmgr-------扫描仪和照相机向导 winchat--------XP... 阅读全文