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---------数学函数 1.绝对值 S:select abs(-1) value O:select abs(-1) value from dual 2.取整(大) S:select ceiling(-1.001) value O:select ceil(-1.001) value from dual 3.取整（小） S:select floor(-1.001) value... 阅读全文
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create table l ( i integer primary key, v varchar(20) ); insert into l values (1, 'one' ); insert into l values (2, 'two' ); insert into l values (3, 'three'); insert into l values (4, 'four' );... 阅读全文
摘要：
A traditional outer join A "normal" join finds values of two tables that are in a relation to each other. In most cases, this relation is equality (=), but it can also be all sorts of operations th... 阅读全文