PDO UNION用？ 不工作

Question

I am new to SQL and PDO and PHP so I know I am asking a lot of myself. Still nothing ventured... I want to combine the results of two queries and am using aliases to make the column names the same for the UNION query. I have tried all sorts of reducing till there is nothing left to reduce, there are many more in the actual result I need for my app. I have the following code by can't think why it is not working.

Both queries work on their own but I get nothing when I combine them with a UNION. Any suggestions would be most helpful.

include ("conn/dbCon_1.php");
$sql= "(SELECT  First_Name AS myResult FROM tbl_User WHERE First_Name LIKE ?)";
$sql.=" UNION ALL ";
$sql.= "(SELECT Course_Title AS myResult FROM tbl_Course  WHERE Course_Title LIKE ? )";
$c1 =  "%le%";
try {
    $qResults = $dbConn->prepare($sql); 
    $qResults->execute([$c1]); 
    $qResults->fetch(PDO::FETCH_ASSOC);
    return $qResults;
    //Close connection
    $dbConn = null;
} catch(PDOExcepetion $e) {
    echo $e->getMessage();
}

Many thanks in anticipation and thank you for your kind attention.

Bri

Answer 1

由于您有两个占位符 - 您应该将值绑定两次 ：

$qResults->execute([$c1, $c1]);

Answer 2

您使用两个参数调用查询（例如在第一个查询中，在第二个查询中调用，即使它们具有相同的值），因此您必须传递两个参数

$qResults->execute([$c1, $c1]);