Oracle 创建函数实例

1、创建函数

create [or replace] function function_name
[(parameter_name [in | out | in out] type [,...])]
retutn type
is|as
begin
 function_body;
end;

说明：函数必须有返回值。
or replace：如果函数已经存在，则替换现有的函数；
function_name：函数名；
parameter_name ：参数名；
in | out | in out：指定参数的模式；
function_body：包含执行任务函数的SQL和PL/SQL语句。
2、函数实例

create or replace function get_publicholidaytime(fromtime in Date, totime in Date, isAvailable in number) return number 
as
  --定义变量
  free_day number :=0;
  mindate Date;
  maxdate Date;
  total number :=0;
  fromdate Date := TO_DATE(to_char(fromtime,'yyyy/MM/dd'),'yyyy/MM/dd');
  todate Date := TO_DATE(to_char(totime,'yyyy/MM/dd'),'yyyy/MM/dd');
begin
  --if语句
  if isAvailable=1 then
    --sql语句
    select min(calendar_date) ,max(calendar_date),count(calendar_date) into mindate,maxdate,total 
    from T_BI_TNT_DATE 
    where calendar_date between fromdate and todate
    and IS_PUBLIC_HOLIDAY=1 ;
    if mindate = fromdate then 
       total := total - 1;free_day := free_day + ((mindate + 1) - fromtime);
    end if;
    if maxdate = todate then
       total := total - 1;free_day := free_day + (totime - maxdate);
    end if;
    if mindate = maxdate then 
       free_day := totime - fromtime;
    else
       free_day := free_day + total;
    end if;
  end if;
  return free_day;
end get_publicholidaytime;

3、调用函数

select get_publicholidaytime(sysdate,sysdate + 1,1) from dual;

4、删除函数

drop function get_publicholidaytime;