查询中的查询是否可以在pdo中进行？

Question

在pdo中可以查询查询吗？

我想从单个查询中的两个表中获取或操作数据。有可能吗？

例：    SELECT * FROM t1 WHERE id = (SELECT id FROM t2 where column > 3 );

如果是这样，我是否也可以对两个表进行绑定。

Answer 1

使用两个表显示参数的PDO绑定，为20岁或以下的人返回数据。

模式

create table person
(   id int auto_increment primary key,
    fullname varchar(100) not null,
    age int not null
);

create table transactions
(   id int auto_increment primary key,
    personId int not null,
    transType varchar(10) not null,
    amount decimal(12,2) not null,
    foreign key fk_trans_per (personId) references person(id)
);

insert person(fullname,age) values 
('Kim Billings',10),('Jason Cartwright',14),('xxx',1),('Older gent',40);

truncate table transactions;
insert transactions(personId,transType,amount) values
(1,'deposit',100),(1,'withd',11),(1,'withd',12),(1,'deposit',120),
(2,'deposit',10),(2,'deposit',20),(2,'xyz',12),(2,'deposit',30),
(4,'deposit',10);

PHP

<?php
    // turn on error reporting, or wonder why nothing is happening at times
    //mysqli_report(MYSQLI_REPORT_ALL);
    mysqli_report(MYSQLI_REPORT_ERROR | MYSQLI_REPORT_STRICT);
    error_reporting(E_ALL);
    ini_set("display_errors", 1);    // Begin Vault

    // credentials from a secure Vault, not hard-coded
    $servername="hostname";
    $dbname="dbname";
    $username="dbuser";
    $password="password";
    // End Vault

    try {
        $db = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
        $db->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
        $db->setAttribute(PDO::ATTR_EMULATE_PREPARES, false);

        $maxAge=20;
        $theType="deposit";

        // return deposit totals for people 20 or younger

        $sql="select p.id,sum(t.amount) as total from person p join transactions t on t.personId=p.id";
        $sql.=" where p.age <= :maxAge and t.transType=:ttype";
        $sql.=" group by p.id";

        $stmt = $db->prepare($sql);
        $stmt->bindParam(':maxAge', $maxAge, PDO::PARAM_INT);
        $stmt->bindParam(':ttype', $theType, PDO::PARAM_STR, 10);
        $stmt->execute();


        // http://php.net/manual/en/pdostatement.fetch.php
        while ($row = $stmt->fetch(PDO::FETCH_ASSOC)) {
            echo "id=".$row['id'] .",   total=".$row['total']."<br>";
        }

        // .. other cleanup as necessary

    } catch (PDOException $e) {
        echo 'PDO error: ' . $e->getMessage();
        exit();
    }
?>

输出

id=1, total=220.00
id=2, total=60.00

Answer 2

您可以使用PDO::query - 执行自定义的SQL语句

<?php
$servername="hostname";
$dbname="dbname";
$username="dbuser";
$password="password";
$db = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
$row = $db->query("SELECT * FROM t1 WHERE id = (SELECT id FROM t2 where column > 3 )")->fetchAll(PDO::FETCH_ASSOC);
echo "<pre>";
var_dump($row);
echo "</pre>";