Question

我的sql代码有一个小问题，更具体地说，是由触发器执行的函数中的问题。

我尝试在if中仅使用1个select（每个查询的if都不同），但是错误仍然相同。我完成的其他功能使用相同类型的查询，不会返回此问题。

CREATE OR REPLACE FUNCTION TIME_UPDATE() RETURNS TRIGGER AS $$
DECLARE IDPART INT;
DECLARE VENC INT;
DECLARE PERD INT;
BEGIN

SELECT INTO IDPART OLD.IDPARTIDAS FROM PARTIDAS WHERE OLD.IDPARTIDAS = NEW.IDPARTIDAS;
SELECT INTO VENC OLD.VENCEDOR FROM PARTIDAS WHERE OLD.IDPARTIDAS = NEW.IDPARTIDAS;
SELECT INTO PERD OLD.PERDEDOR FROM PARTIDAS WHERE OLD.IDPARTIDAS = NEW.IDPARTIDAS;

IF((VENC != (SELECT NEW.VENCEDOR FROM PARTIDAS WHERE IDPART = NEW.IDPARTIDAS))
AND (VENC = (SELECT NEW.PERDEDOR FROM PARTIDAS WHERE IDPART = NEW.IDPARTIDAS)))
THEN
    UPDATE TIME SET OLD.VITORIAS = COALESCE(VITORIAS, 0) - 1, PONTUACAO = COALESCE(PONTUACAO, 0) - 5
    WHERE IDTIME = VENC;
    UPDATE TIME SET DERROTAS = COALESCE(DERROTAS, 0) + 1, PONTUACAO = COALESCE(PONTUACAO, 0) - 2
    WHERE IDTIME = VENC; 
END IF;

IF((PERD != (SELECT NEW.PERDEDOR FROM PARTIDAS WHERE IDPART = NEW.IDPARTIDAS))
AND (PERD = (SELECT NEW.VENCEDOR FROM PARTIDAS WHERE IDPART = NEW.IDPARTIDAS)))
THEN
    UPDATE TIME SET OLD.VITORIAS = COALESCE(VITORIAS, 0) + 1, PONTUACAO = COALESCE(PONTUACAO, 0) + 5
    WHERE IDTIME = PERD;
    UPDATE TIME SET DERROTAS = COALESCE(DERROTAS, 0) - 1, PONTUACAO = COALESCE(PONTUACAO, 0) + 2
    WHERE IDTIME = PERD;
END IF;

    UPDATE TIME SET OLD.VITORIAS = COALESCE(VITORIAS, 0) - 1, PONTUACAO = COALESCE(PONTUACAO, 0) - 5
    WHERE IDTIME = VENC;
    UPDATE TIME SET OLD.VITORIAS = COALESCE(DERROTAS, 0) - 1, PONTUACAO = COALESCE(PONTUACAO, 0) + 2
    WHERE IDTIME = PERD;
RETURN NEW;

END;
$$ LANGUAGE PLPGSQL;

CREATE TRIGGER ATUALIZAR_PARTIDA AFTER UPDATE ON PARTIDAS FOR EACH ROW EXECUTE PROCEDURE TIME_UPDATE();

错误：

错误：子查询返回的多于一行用作表达式---------------上下文：SQL语句“ SELECT（（VENC！=（SELECT NEW.VENCEDOR FROM PARTIDAS IDPART = NEW.IDPARTIDAS））和（VENC =（从PARTIDAS中选择NEW.PERDEDOR，IDPART = NEW.IDPARTIDAS）））---------------------- PL / pgSQL函数time_update（）第11行位于IF --------------------------------------- -------------------- SQL状态：21000

Answer 1

此比较：

VENC != (SELECT NEW.VENCEDOR FROM PARTIDAS WHERE IDPART = NEW.IDPARTIDAS

和与此类似的其他记录，必须返回一条记录。您可以手动运行所有这些查询，直到发现该查询返回多个记录为止。

Answer 2

您的整个触发器代码在某些地方是复杂和错误的方法。

要从select语句分配变量，您需要使用select column_name into variable from ... 不 select into variable ...
无需使用选择语句开始“复制”新记录或旧记录的值。实际上，根本不需要复制这些值。
如果要引用new或old记录中的列，则不需要select语句。
您不需要两个update语句来更新两个列，这可以通过一个语句来完成。
您不能将old记录中的列用作UPDATE语句的目标列，SET OLD.VITORIAS = ...是无效的，令我惊讶的是它甚至可以编译。我认为您打算写set vitorias = ....
在IF语句中对vitorias列的更新被两个IF块之后的无条件更新覆盖。并且在最后一次UPDATE的情况下，其值也完全不同。

删除所有错误或不必要的代码，我想您正在寻找的是

CREATE OR REPLACE FUNCTION TIME_UPDATE() 
RETURNS TRIGGER 
AS 
$$
DECLARE 
  VENC INT;
  PERD INT;
BEGIN
    -- this is useless. All references to "venc" or "perd" can 
    -- directly be replaced with a reference to the old record.
    venc := old.vencedor;
    perd := old.perdedor;

    IF (new.vencedor <> old.vencedor)
    THEN
        UPDATE time 
            SET vitorias = coalesce(vitorias, 0) - 1, pontuacao = coalesce(pontuacao, 0) - 5,
                derrotas = coalesce(derrotas, 0) + 1, pontuacao = coalesce(pontuacao, 0) - 2
        WHERE idtime = venc; 
    END IF;

    IF (new.perdedor <> old.perdedor) 
    THEN
        UPDATE time 
            SET vitorias = coalesce(vitorias, 0) + 1, pontuacao = coalesce(pontuacao, 0) + 5,
                derrotas = coalesce(derrotas, 0) - 1, pontuacao = coalesce(pontuacao, 0) + 2
        WHERE idtime = perd;
    END IF;

    -- this overwrites the change done in the first IF block with the same value
    UPDATE TIME 
       SET vitorias = coalesce(vitorias, 0) - 1, pontuacao = coalesce(pontuacao, 0) - 5
    WHERE IDTIME = venc;

    -- this overwrites the change done in the second IF block with a different(!) value
    UPDATE TIME 
        SET vitorias = coalesce(derrotas, 0) - 1, pontuacao = coalesce(pontuacao, 0) + 2
    WHERE idtime = perd;

    RETURN NEW;
END;
$$ LANGUAGE PLPGSQL;

错误：由子查询返回的多行用作表达式pgadmin

2 个答案: