Postgresql - 測試記錄類型（對於字段或null）

Question

我在處理plpgsql和RECORD類型時遇到了問題。

有誰知道一種方法來簡單地測試返回的記錄類型，以知道它是否設置？

基本模式：

甲函數返回一個記錄，並在那裏它可以是未固化的（即，選擇到沒有記錄返回）或它被設置爲一個單個記錄。

create or replace function blah() 
returns RECORD as $$ 
declare 
    rec RECORD; 
begin 
    rec := row(null); --Do not want to hear about it not being assigned 
    select *, status_field into rec ... ; 
    if found then 
     raise notice '%', rec.status_field is not null --prints 't' 
    end if 

    if not found then 
     raise notice '%', rec.status_field is not null --Throws Error (I just want it to say 'f' 
    end if; 
end; $$ 

create or replace function callblah() 
returns text as $$ 
declare 
    rtText text; 
    blahRec RECORD; 
begin 
blahRed := blah(...); 

-- what test can I do to determine if record is set or not. 
-- Try: if blah is not null then -- nope always returns false for is null and is not null 
-- Try: if blah.status is not null then -- nope throws error on field not existing 
-- What test condition do I need to add here to simply test if record is either (NOT FOUND) or (FOUND where field will exist). 
... 
end if 
end; $$ 

Answer 1

對於RECORD，Ah ..是null操作符是（所有字段爲空），而不是null（所有字段都不爲空）。由於我有一些字段爲null，我需要做

if blah is null then 
    -- No record found 
else 
    if blah.status is not null then 
    -- Record found with field I want 
    end if; 
end if;