PHP MySQL从同一结果行获取列作为不同的数组

Question

假设，我有一个事件表，我想获取某一天的所有事件（例如 2018-01-02）

|   e1    |     d1     |   e2    |     d2     |   e3    |     d3     |
----------------------------------------------------------------------
| event A | 2018-01-01 | event B | 2018-01-02 | event C | 2018-01-02 |
| event D | 2018-01-01 | NULL    | NULL       | NULL    | NULL       |
| NULL    | NULL       | event E | 2018-01-02 | event F | 2018-01-03 |

问题是当我尝试获取这样的结果时：

"SELECT * FROM table WHERE d1='2018-01-02' OR d2='2018-01-02' OR d3='2018-01-02' "

我得到了整行结果（在这种情况下 - 所有三行）。 但我想获得带有事件和日期的单独结果数组。像这样：

Array
(
    [0] => Array
        (
            event => event B
            date => 2018-01-02
        )
    [1] => Array
        (
            event => event C
            date => 2018-01-02
        )
)

就目前而言，我以这种丑陋的方式做到了，执行 3 个查询并加入它们的结果：

$Sql=$conn->prepare("SELECT e1 AS event, d1 AS date FROM table WHERE d1='2018-01-02'");
$Sql->execute();
$Arr1 = $Sql->fetchAll(PDO::FETCH_ASSOC);

$Sql=$conn->prepare("SELECT e2 AS event, d2 AS date FROM table WHERE d2='2018-01-02'");
$Sql->execute();
$Arr2 = $Sql->fetchAll(PDO::FETCH_ASSOC);

$Sql=$conn->prepare("SELECT e3 AS event, d3 AS date FROM table WHERE d3='2018-01-02'");
$Sql->execute();
$Arr3 = $Sql->fetchAll(PDO::FETCH_ASSOC);

$Arr=array();
foreach($Arr1 AS $a){
 $Arr[]=array($a['event'],$a['date']);
}
foreach($Arr2 AS $a){
 $Arr[]=array($a['event'],$a['date']);
}
foreach($Arr3 AS $a){
 $Arr[]=array($a['event'],$a['date']);
}

print_r($Arr);

但我确信应该有一些更充分的方法来做到这一点。通过修改 SQL 或 PHP。 提前致谢。

Answer 1

看看https://dev.mysql.com/doc/refman/5.7/en/union.html 试试这样的

$Sql=$conn->prepare("(SELECT e1 AS event, d1 AS date FROM table WHERE d1='2018-01-02') UNION (SELECT e2 AS event, d2 AS date FROM table WHERE d2='2018-01-02') UNION (SELECT e3 AS event, d3 AS date FROM table WHERE d3='2018-01-02') ");
$Sql->execute();
$Arr = $Sql->fetchAll(PDO::FETCH_ASSOC);

还请注意，日期是reserved word，因此您可能必须用反引号来写它...虽然不确定，因为我根本不使用它们；）