Oracle的dual表作用
1、查看当前用户,可以在 SQL Plus中执行下面语句select user from dual;2、用来调用系统函数select to_char(sysdate,
1、查看当前用户,可以在 SQL Plus中执行下面语句
select user from dual;
2、用来调用系统函数
select to_char(sysdate,'yyyy-mm-dd hh24:mi:ss') from dual;——获得当前系统时间
select SYS_CONTEXT('USERENV',,'TERMINAL') from dual;——获得主机名
select SYS_CONTEXT('USERENV','language') from dual;——获得当前locale
select dbms_random.random from dual;——获得一个随机数
3、得到序列的下一个值或当前值,用下面语句
select your_sequence.nextval from dual;——获得序列your_sequence的下一个值
select your_sequence.currval from dual;——获得序列your_sequence的当前值
4、可以用做计算器
select 7*9 from dual;

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