oracle常用函數
to_date()函數使用
select * from pstrwo where ech_date = to_date('20171211','yyyymmdd');
lower把字符串轉化爲小寫
select lower(name) from emp;
upper把字符串轉化爲大寫
select upper(name) from emp
replace 替換字符
select replace(name,'A','A') from emp 把名字中的A轉化爲a
length返回字符串長度
select * from emp where length(name) = 5 顯示正好爲5個字符的名字
substr()截取字符串
select substr(name,1,1) from emp; 截取名字的首字母,從第一位開始截取一位字符
顯示姓名首字母大寫,其餘小寫
select upper(substr(name,1,1)) from emp;
select lower(substr(name,2,length(name)-1)) from emp;
select upper(substr(name,1,1)) || lower(substr(name,2,length(name)-1)) from emp;
sysdate 返回系統時間
select sysdate from dual;
to_char(字符串,類型):把數據轉換爲字符串類型
select to_char(sysdate,'yyyy/mm/dd hh24:mi:ss') from dual;
select * from emp where to_char(emp.hiredate,'yyyy')=1980;
sys_guid()
select sys_guid() from dual;返回一個類似於UUID的唯一標識