Question

SQL问题。我目前有两个SQL表，一个名为Waitlist，一个名为Booking。它们不相同（等待列表包含的信息比预订更多）。他们看起来像这样：

候补：

#   Customer    Day                 Timestamp                   Flight
1   Joseph     2017-04-22      2017-04-22 16:20:33.178     F101

售票：

#   Customer    Flight  Day
1   Timmy   F101    2017-04-22
2   Joseph  F101    2017-04-22

我想从waitlist中删除重复数据（在本例中为joseph条目）....我尝试了以下内容： DELETE FROM Waitlist WHERE Customer = booking.customer and day = booking.day and flight = booking.flight 我也试过INNER JOIN而没有运气。请帮助!!

Answer 1

有多种方法可以实现您的目标，但对您的问题最恰当的答案是数据库供应商特定。

即。在MySQL和SQL Server中，您可以直接在JOIN语句

中使用DELETE

DELETE w 
  FROM waitlist w JOIN booking b 
    ON w.customer = b.customer
   AND w.day = b.day
   AND w.flight = b.flight;

Sqlfiddle用于MySql，Sqlfiddle用于SQL Server

在PostgreSQL中，您可以利用EXISTS

DELETE FROM waitlist w
 WHERE EXISTS (
     SELECT *
       FROM booking
      WHERE customer = w.customer
        AND day = w.day
        AND flight = w.flight
);

SqlFiddle

SQL删除类似的条目

1 个答案: