ORACLE生成惟一标识函数

-- Create table
create table TAB_TEST
(
id VARCHAR2(40) not null,
fxnum VARCHAR2(40)
)

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create or replace function f_GetFxNum
return nvarchar2
as
FxNum nvarchar2(16);
begin
SELECT 'FX'||(NVL(MAX(SUBSTR(FxNum,3,14)),TO_CHAR(SYSDATE,'YYYYMMDD')||'000000')+1) into FxNum FROM TAB_TEST WHERE SUBSTR(FxNum,3,8)=TO_CHAR(SYSDATE,'YYYYMMDD') ;
return FxNum;
end;

 

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select f_GetFxNum() from dual