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  • --关于null在oracle数据库中是否参与计算,进行验证,

    --关于null在oracle数据库中是否参与计算,进行验证,
    with td as (
    select null id,1 name from dual
    ),
    td1 as
    (
    select null id,2 name from dual )


    select * from td, td1 where nvl(td.id,'0.00') = '0'


    select '1'||'0.1' from dual
    number
    number -> char
    select to_char(3333.00,'999,999,009.00') from dual
    to_char ;
    to_date ;
    to_number ;
    3333.00
    select to_char(3.00,'fm9990999') from dual
    jsp ####,000
    partten = '#################0000'
    3
    03
    select nvl(null,0.00) from dual ;
    null 不参与计算

    = 来比较时, 两边类型不一样,就向下转型
    select sysdate from dual where 0 = 0 ;
    select sysdate from dual where '0' = '0' ;
    number ---char
    char --number

    nvl(td1.id,0);
    null bu cnayu jis
    group by
    select sum(id) from td;
    1
    select 1+null from dual
    null 不参与计算

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  • 原文地址:https://www.cnblogs.com/wglwgl/p/6033470.html
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