Oracle管道函数pipelined function的用法小结

CREATE OR REPLACE Type test_Row_Type As Object
(
  test1 Varchar2(512),
  test2 Varchar2(3000),
  test3 Varchar2(3000),
  test4 Varchar2(3000),
  test5 Varchar2(3000),
  test6 Number,
  test7 Number
)

CREATE OR REPLACE TYPE test_Row_Type_TABLE AS TABLE OF test_Row_Type;

create table TTTtable
(
  aaa VARCHAR2(50),
  bbb VARCHAR2(50),
  ccc VARCHAR2(50)
)

CREATE OR REPLACE FUNCTION test_Row_pipelined(p_varchar in varchar2)
  return test_Row_Type_TABLE
  --关键字加在这里
  pipelined as
  p_num integer := 0;
  ret   test_Row_Type;
begin
  --查询临时表数据
  for sub_data in (select t.bbb, t.ccc
                     from TTTtable t
                    where t.aaa = p_varchar) loop
    p_num := p_num + 1;
    ret := test_Row_Type(p_num,
                             sub_data.bbb,
                             sub_data.ccc,
                             '',
                             '',
                             0,
                             0);
    --将数据放入管道，pipe row()语法被用来返回该集合的单个元素
    pipe row(ret);
  end loop;
  --函数使用一个空的return结束
  return;
end;

select test_Row_pipelined('a') from dual

select * from table(test_Row_pipelined('a')) t

select t.* from table(test_Row_pipelined('a')) t where t.test1 = 1

CREATE OR REPLACE FUNCTION test_Row_pipelined(p_insvar    in varchar2,
                                                  p_delimiter in varchar2)
  return test_Row_Type_TABLE
  pipelined as
  p_num     integer := 1;
  p_num1    integer;
  p_length  integer;
  p_start   integer := 1;
  p_varchar varchar2(200);
  ret       test_Row_Type;
begin
  --如果不是以分隔符结尾的，就拼接上去
  select case
           when (select count(1)
                   from dual
                  where p_insvar like '%' || p_delimiter) > 0 then
            p_insvar
           else
            p_insvar || p_delimiter
         end
    into p_varchar
    from dual;
  --整个字符串的长度
  select length(p_varchar) into p_length from dual;
  --当起始长度大于整体长度的时候
  while (p_start <= p_length) loop
    --找到字符串与分隔符的分割后的下标
    select instr(p_varchar, p_delimiter, p_start) into p_num1 from dual;
    --如果没有，则返回全部字符串，说明到了结尾了
    if p_num1 = 0 then
      ret := test_Row_Type(p_num,
                               substr(p_varchar, p_start),
                               p_num1,
                               p_start,
                               p_length,
                               0,
                               0);
      pipe row(ret);
    else
      --否则，截取字符传中，从p_start开始找到下标减去p_start的部分
      ret := test_Row_Type(p_num,
                               substr(p_varchar, p_start, p_num1 - p_start),
                               p_num1,
                               p_start,
                               p_length,
                               0,
                               0);
      pipe row(ret);
     --新的起始点为下标加1
      p_start := p_num1 + 1;
    end if;
    --序号加1
    p_num := p_num + 1;
  end loop;
  return;
end;