Question

我有这个查询在MYSQL中工作，但不能在SQLite中运行。我认为它失败是因为WHERE子句中有多个参数。

目的是为所有调查问题（sqid）选择唯一的最新调查答案（所述），因为可能会有多个问题答案。

SELECT sqid, said, saname, satimestamp
FROM surveyanswer 
WHERE (sqid, hoid, satimestamp) IN (
    SELECT sqid, hoid, max(satimestamp) as satimestamp
    FROM surveyanswer
    GROUP BY sqid
)

我已经尝试过satimestamp的排序并选择了一个而不是max的限制但是无法使其工作。

Answer 1

您可以通过加入来执行此操作：

SELECT sqid, said, saname, satimestamp
FROM surveyanswer A
JOIN (
    SELECT sqid, hoid, max(satimestamp) as satimestamp
    FROM surveyanswer
    GROUP BY sqid
) B ON A.sqid = B.sqid and A.hoid = B.hoid and A.satimestamp = B.satimestamp

这在功能上与原始SQL类似，但由于您只关心时间，我相信这也会起作用：

SELECT sqid, said, saname, satimestamp
FROM surveyanswer A
JOIN (
    SELECT max(satimestamp) as satimestamp
    FROM surveyanswer
) B ON A.satimestamp = B.satimestamp

Answer 2

您似乎没有使用hoid字段进行任何操作。所以，我删除了它。以下是否能满足您的需求：

SELECT sa.sqid, sa.said, sa.saname, sa.satimestamp
FROM surveyanswer sa
WHERE sa.satimestamp IN (
    SELECT max(subsa.satimestamp)
    FROM surveyanswer subsa
    WHERE sa.sqid = subsa.sqid
)

如果hoid字段需要包含在where子句中，请尝试以下操作：

SELECT sa.sqid, sa.said, sa.saname, sa.satimestamp
FROM surveyanswer sa
WHERE sa.satimestamp IN (
    SELECT max(subsa.satimestamp)
    FROM surveyanswer subsa
    WHERE sa.sqid = subsa.sqid
    AND sa.hoid = subsa.hoid
)

SQLite在WHERE中传递多个参数

2 个答案: