Question

我正在尝试创建一个触发器，该触发器会设置一个功能，以便在将图书的货件插入表格货件时检查是否有足够的库存。如果库存不足，则会引发异常，否则库存减少1。

这是我的代码：

CREATE FUNCTION decstock() RETURNS trigger AS $pname$
    BEGIN

        IF (SELECT stock FROM stock WHERE stock.isbn = NEW.ISBN) = 0 THEN
            RAISE EXCEPTION 'There is no stock to ship'
        ELSE
            UPDATE stock
            SET stock = stock-1
            WHERE stock.isbn = NEW.isbn;
        END IF;
    END;
$pname$ LANGUAGE plpgsql;

CREATE TRIGGER hej
BEFORE UPDATE ON shipments
FOR EACH ROW /*Why on each row? Aren't we supposed to only look at the stock for the specified isbn? Also, how do I reference the stock table here?*/
EXECUTE PROCEDURE decstock();

运行时遇到错误，它说：

ERROR:  syntax error at or near "ELSE"
LINE 7:   ELSE
          ^

********** Error **********

ERROR: syntax error at or near "ELSE"
SQL state: 42601
Character: 181

我找不到我在这里做的语法错误。有什么提示吗？

Answer 1

RAISE EXCEPTION '....'必须以分号结束，就像任何其他pl / pgsql语句一样。

Postgresql，IF子句中的语法错误

1 个答案: