SQL 积累

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查询多个结果一起使用

SELECT X.a,F.b from (select (3-2) a from dual) X,(select (4-2) b FROM dual) F;

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查询结果的表在与其他表使用

select * from (
with pro as (
   SELECT distinct first_sequence
      FROM parametric_measure
      WHERE
           measure_name = 'DATE' ),
bbb as (select b.measure_name 测试参数,b.description 测试内容
          from pro p inner join parametric_measure b on (b.first_sequence = p.first_sequence and b.measure_name = 'HUMIDITY')
     inner join parametric a on (a.handle = b.parametric_bo)
     INNER JOIN RESRCE C ON(A.SITE = C.SITE AND SPLIT(A.PARA_CONTEXT_GBO,2) = C.RESRCE AND A.SITE = '1000') )
     select * from bbb)

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SQL中时间计算得到值

SELECT ROUND(TO_NUMBER( TO_DATE('2013-07-04 05:10:28','YYYY-MM-DD hh24:mi:ss') - TO_DATE('2013-07-04 02:58:28','YYYY-MM-DD hh24:mi:ss') ) * 24 ) SJ
from dual 得到小时

有两个日期数据START_DATE，END_DATE，欲得到这两个日期的时间差（以天，小时，分钟，秒，毫秒）：

　　天：

　　ROUND(TO_NUMBER(END_DATE - START_DATE))

　　小时：

　　ROUND(TO_NUMBER(END_DATE - START_DATE) * 24)

　　分钟：

　　ROUND(TO_NUMBER(END_DATE - START_DATE) * 24 * 60)

　　秒：

　　ROUND(TO_NUMBER(END_DATE - START_DATE) * 24 * 60 * 60)

　　毫秒：

　　ROUND(TO_NUMBER(END_DATE - START_DATE) * 24 * 60 * 60 * 60)

解决Oracle 11g在用EXP导出时，空表不能导出

declare
stmt varchar2(200);
begin
for tb in (select table_name from user_tables) loop
stmt:='alter table '||tb.table_name||' allocate extent';
execute immediate stmt;
end loop;
end;
/

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