mysql - 时间戳..只需要第一个和最后一个

Question

我有一个返回估计日期和时间戳的查询。每个估计可以有多个时间戳。我只需要第一张和最后一张邮票。我怎样才能做到这一点？我的查询如下所示:

SELECT LogDateTime, Operator, Program, Explanation, TransactionCode
FROM SystemLog
WHERE Program = 'Estimating'
ORDER BY TransactionCode

Answer 1

使用 min() 和 max() 聚合函数:

SELECT
    min(LogDateTime) as first_LogDateTime,
    max(LogDateTime) as last_LogDateTime,
    Operator, Program, Explanation, TransactionCode
FROM SystemLog
WHERE Program = 'Estimating'
GROUP BY Operator, Program, Explanation, TransactionCode
ORDER BY TransactionCode