PostgreSQL function里面调用function

create or replace function func01()returns void as $$
begin
raise notice ' from func01(): hello PG';
end ;
$$language plpgsql;

create or replace function func02() returns void as $$
begin
perform  func01();
end;
$$language plpgsql;

select  func02();

注意:   from func01(): hello PG
CONTEXT:  SQL statement "SELECT func01()"
在PERFORM的第3行的PL/pgSQL函数"func02"

查询总耗时: 14 ms.
检索到 1 行。

create or replace function func03()returns integer as $$
begin
return 1;
end ;
$$language plpgsql;

create or replace function func02() returns void as $$
begin
perform  func03();
end;
$$language plpgsql;

create or replace function func02() returns void as $$
declare n int;
begin
select into n func03();
raise notice 'n: %',n;
end;
$$language plpgsql;

select  func02();

注意:  n: 1

查询总耗时: 12 ms.
检索到 1 行。

create or replace function func04(n int)returns integer as $$
begin
return n;
end ;
$$language plpgsql;

create or replace function func02() returns void as $$
declare n int;
begin
n=func04(4);
raise notice 'n: %',n;
end;
$$language plpgsql;

select  func02();

注意:  n: 4

查询总耗时: 11 ms.
检索到 1 行。