插入触发器SQL:表的子句项中缺少

我正在使用Postgres，并试图创建一个触发器，用于在表中插入或更新新值

以下是触发器和函数：

create or replace function trigf1() returns trigger as $$
begin
if (ballotbox.totvoters>votes.nofvotes) then 
raise notice 'more voters than allowed';
return old;
else return new; 
end if;
end;
$$ language plpgsql;

create trigger T1 
Before insert or update on votes
for each row 
execute procedure trigf1();

当我试图更新表“投票”和“选票箱”时，我得到了错误：

ERROR:  missing FROM-clause entry for table "ballotbox"
LINE 1: SELECT (ballotbox.totvoters > votes.nofvotes)
                ^
QUERY:  SELECT (ballotbox.totvoters > votes.nofvotes)
CONTEXT:  PL/pgSQL function trigf1() line 3 at IF

我不知道是否需要，但以下是创建表和插入值：

create table ballotBox
(bno integer,
cid numeric(4,0),
street varchar(20),
hno integer,
totvoters integer,
primary key (bno),
foreign key (cid) references city);

create table votes
(cid numeric(4,0),
bno integer,
pid numeric(3,0),
nofvotes integer,
foreign key (cid) references city,
foreign key (bno) references ballotBox,
foreign key (pid) references party,
check (nofvotes >= 0));

insert into ballotBox values
(1, 1, 'street1', 10, 1500),
(2, 1, 'street2', 15, 490),
(3, 1, 'street2', 15, 610),
(4, 1, 'street2', 15, 650),
(5, 2, 'street3', 10, 900),
(6, 2, 'street3', 55, 800),
(7, 2, 'street4', 67, 250),
(8, 2, 'street4', 67, 990),
(9, 2, 'street5', 5, 600),
(10, 3, 'street1', 72, 1000),
(11, 3, 'street6', 25, 610),
(12, 3, 'street6', 25, 600),
(13, 4, 'street2', 3, 550),
(14, 4, 'street7', 15, 500),
(15, 5, 'street8', 44, 1100),
(16, 5, 'street9', 7, 710),
(17, 5, 'street10', 13, 950);

insert into votes values
(1, 1, 200, 100),
(1, 1, 210, 220),
(1, 1, 220, 2),
(1, 1, 230, 400),
(1, 1, 240, 313),
(1, 1, 250, 99),
(2, 1, 200, 55),
(2, 1, 210, 150),
(2, 1, 220, 2),
(2, 1, 230, 16),
(2, 1, 240, 210);

试试这个

if ((select totvoters from ballotbox) > (selecct nofvotes from votes))

---

必须使用

NEW

（）引用插入的行。由于表

ballotbox

将包含许多行，问题是您希望将这些值与其中的哪一行进行比较？您需要运行一个select语句来获取所需的值并将其存储在变量中。有关详细信息，请参阅手册：