Question

我将此查询运行到GROUP BY session_id并获取最新（时间）记录：

$query = "SELECT type, session_id, session_name, session_email, time
FROM chat
WHERE time IN (
    SELECT MAX(time)
    FROM chat
    GROUP BY session_id
)
ORDER BY time DESC";

然而，我只想要最新的类型和时间记录。我怎样才能获得session_id，session_name，session_email的第一条记录？

Answer 1

    $query = "
    SELECT type, session_id, session_name, session_email, time
    FROM chat
    WHERE time IN
    (
        SELECT MAX(time)
        FROM chat
        GROUP BY session_id
    )
    ORDER BY time DESC
    LIMIT 5 /* gives you the first 5 records

    UNION

    SELECT type, session_id, session_name, session_email, time
    FROM chat
    WHERE time IN
    (
        SELECT MAX(time)
        FROM chat
        GROUP BY session_id
    )
    ORDER BY time ASC
    LIMIT 5 /* gives you the first 5 records in other sequence
    ";

PHP / Mysqli - GROUP BY获取最新记录，但仅限于某些记录

1 个答案: