创建触发器函数是 psql "syntax error at or near "CREATE""

Question

这是我的 postgreSQL 代码

CREATE FUNCTION connectedExhibitionFunction()
RETURNS trigger AS
$$
BEGIN
        IF (SELECT COUNT("exName") FROM Exhibitions WHERE NEW."exName" = "exName") > 0 THEN
                IF (SELECT Count(doorLoc1) FROM Doors, ExhibitionLocations WHERE (dorLoc1=NEW.elLocation AND dorLoc2=elLocations) OR (dorLoc2=NEW.elLocation AND dorLoc1=elLocations) > 0 THEN
                        RAISE EXCEPTION 'You can't have the exhibition there, the same exhibition is in an unconnected room';
                END IF;
        END IF;
END;
$$
LANGUAGE plpgsql;

CREATE TRIGGER connectedExhibitionTrigger
        BEFORE INSERT
        ON ExhibitionsLocations
        EXECUTE PROCEDURE connectedExhibitionFunction();

这就是我遇到的错误

psql:file.txt:62: ERROR:  syntax error at or near "CREATE"
LINE 8: CREATE FUNCTION connectedExhibitionFunction()
        ^
psql:file.txt:67: ERROR:  current transaction is aborted, commands ignored until end of transaction block

我似乎无法找出错误，有人能在这里发现什么吗？

Answer 1

我猜你错过了 Select ")" 并且不能提出例外条款 "can't" 您可以只使用 END 而不是 END IF。据我所知你的问题是这些。

请试试这个。

 IF (SELECT Count(doorLoc1) FROM Doors, ExhibitionLocations 
  WHERE (dorLoc1=NEW.elLocation AND dorLoc2=elLocations) OR 
  (dorLoc2=NEW.elLocation AND dorLoc1=elLocations)) > 0 THEN
  RAISE EXCEPTION 'You cant have the exhibition there, the same exhibition is in an unconnected room';
 END

Answer 2

您不应使用 count() 函数来测试数据是否存在，而应使用 PERFORM 命令。您还应该 RETURN NEW 或 RETURN NULL 来自触发器函数，否则您的插入将根据定义失败。通过其他一些改进，您将得到这样的结果：

CREATE FUNCTION connectedExhibitionFunction() RETURNS trigger AS $$
BEGIN
    PERFORM * FROM Exhibitions WHERE "exName" = NEW."exName";
    IF FOUND THEN
        PERFORM * FROM Doors, ExhibitionLocations
        WHERE (dorLoc1 = NEW.elLocation AND dorLoc2 = elLocations)
           OR (dorLoc2 = NEW.elLocation AND dorLoc1 = elLocations);
        IF FOUND THEN
            RAISE EXCEPTION 'You can''t have the exhibition there, the same exhibition is in an unconnected room';
            RETURN NULL; -- Make the INSERT fail
        END IF;
    END IF;
    RETURN NEW; -- Make the INSERT succeed
END;
$$ LANGUAGE plpgsql;

创建触发器函数是 psql "syntax error at or near "CREATE""

Creating Trigger function is psql "syntax error at or near "CREATE""

sql

postgresql

triggers

psql