mysql - 时间戳..只需要第一个和最后一个

Question

我有一个查询返回估计的日期和时间戳。每个估计可以有多个时间戳。我只需要第一个和最后一个印章。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