Oracle 你真的會用ltrim/rtrim函數嗎?,ltrimrtrim

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Oracle 你真的會用ltrim/rtrim函數嗎?,ltrimrtrim

常見的用法是去除空格,有多少人不知道它們其實還可以做到去除空格,它有ltrim()、ltrim(x,y)方法

-------   去兩邊空格,去左空格,去右空格    --------select trim('    X-rapido    ') name from dual;   返回 'X-rapido'select ltrim('    X-rapido    ') name from dual;  返回 'X-rapido    'select rtrim('    X-rapido    ') name from dual;  返回 ''    X-rapido'' select trim(null) name from dual;   返回null


ltrim(x,y)文法

ltrim(x,y) 函數是按照y中的字元一個一個截掉x中的字元,並且是從左邊開始執行的,只要遇到y中有的字元, x中的字元都會被截掉, 直到在x的字元中遇到y中沒有的字元為止函數命令才結束 

select ltrim('abcdabababe','ab') word from dual;

結果:cdabababe

select ltrim('aaaaaa','a') word from dual;

結果:null空

select ltrim('109224323','109') nums from dual;

結果:224323

select ltrim('10900094323','109') nums from dual;

結果:4323

select ltrim('10900111000991110224323','109') nums from dual;

結果:224323

select ltrim('109200111000991110224323','109') nums from dual;

結果:200111000991110224323

select ltrim('902100111000991110224323','109') nums from dual;

結果:2100111000991110224323


注意:Oracle區分大小寫

select ltrim('abcdab','B') word from dual;

結果:abcdab


至於rtrim函數,與ltrim同理,一個從左邊開始,一個從右邊開始


截取字串的功能不同於substr函數,因為一個是指定字元,一個是指定下標


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