Question

如果今天等于保存在数据库中的日期，我正在使用此查询显示结果。

$sh = $db->prepare('SELECT * FROM events WHERE  DATE(:today) = DATE(`start`)');
$sh->bindValue(":today", $today);
$sh->execute();
while($row = $sh->fetch(PDO::FETCH_ASSOC)) { 
here is my code when results are found
}

但是，如果没有结果，我想重复上面的代码，只将查询更改为此

SELECT * FROM events WHERE城市= (:city) AND DATE(:start) Between DATE(开始) and DATE(结束)

这样做的好方法是什么？

谢谢。

Answer 1

如果您想在一个查询中执行此操作，则可以执行以下操作：

SELECT *
FROM events
WHERE  DATE(:today) = DATE(`start`)
union all
SELECT *
FROM events
WHERE city= (:city) AND DATE(:start) Between DATE(start) and DATE(end) and
      not exists (SELECT * FROM events WHERE DATE(:today) = DATE(`start`));

编辑：

如果你想获得3行，按第一个查询排序，而不是第二个，那么这样做：

SELECT *
FROM events
WHERE  DATE(:today) = DATE(`start`) or
       (city= (:city) AND DATE(:start) Between DATE(start) and DATE(end))
order by DATE(:today) = DATE(`start`) desc, rand()
limit 3;

如何检查查询是否返回无结果并使用其他查询？

1 个答案: