how to call a function multiple times with where clause in php pdo?

问题

I am new to php and trying hard to learn its why you guys and gals need to Forgive me for asking a lot!

Here is my question;

I am trying to call a function with where clause multiple times, I have read allmost all posts and examples still didn't understand how to do it.

I tought that An example will be more useful than any blurb I can write.

Here is the function I am trying to create and use it multiple times :

function getTable($tableName, $clause) {
        $stmt = $pdo->prepare("SELECT * FROM ".$tableName." WHERE ".$clause." = :".$clause);
        $stmt->bindParam(":$clause", $clause, PDO::PARAM_STR);
        $stmt->execute();
        if($stmt->rowCount() > 0){
            return true;
        }else{
            return false;
        }
    return $stmt;
}

I am not sure if my fucntion is safe or its rigth.

AND this is how I am trying to call function, which I dont know how to call table name and where clause and how to turn while loop.

getTable('posts');

If you give an example of creating and caling function, I would be grateful, Thanks

回答1:

Nope, your function is not safe. Moreover it is just useless. There is no use case where you would use it like this getTable('posts');. And for the everything else it is much better to allow the full SQL syntax, not some limited subset.

The simplest yet most powerful PDO function I can think of is a function that accepts a PDO object, an SQL query, and array with input variables. A PDO statement is returned. I wrote about such function in my article about PDO helper functions. So here is the code:

function pdo($pdo, $sql, $args = NULL)
{
    if (!$args)
    {
         return $pdo->query($sql);
    }
    $stmt = $pdo->prepare($sql);
    $stmt->execute($args);
    return $stmt;
}

With this function you will be able to run any query, with any number of WHERE conditions, and get results in many different formats. Here are some examples from the article mentioned above:

// getting the number of rows in the table
$count = pdo($pdo, "SELECT count(*) FROM users")->fetchColumn();

// the user data based on email
$user = pdo($pdo, "SELECT * FROM users WHERE email=?", [$email])->fetch();

// getting many rows from the table
$data = pdo($pdo, "SELECT * FROM users WHERE salary > ?", [$salary])->fetchAll();

// getting the number of affected rows from DELETE/UPDATE/INSERT
$deleted = pdo($pdo, "DELETE FROM users WHERE id=?", [$id])->rowCount();

// insert
pdo($pdo, "INSERT INTO users VALUES (null, ?,?,?)", [$name, $email, $password]);

// named placeholders are also welcome though I find them a bit too verbose
pdo($pdo, "UPDATE users SET name=:name WHERE id=:id", ['id'=>$id, 'name'=>$name]);

// using a sophisticated fetch mode, indexing the returned array by id
$indexed = pdo($pdo, "SELECT id, name FROM users")->fetchAll(PDO::FETCH_KEY_PAIR);

Special for you, here is the while example, though this method is considered clumsy and outdated:

$stmt = pdo($pdo,"SELECT * FROM tableName WHERE field = ?",[$value]);
while ($row = $stmt->fetch()) {
    echo $row['name'];
}

来源：https://stackoverflow.com/questions/58856805/how-to-call-a-function-multiple-times-with-where-clause-in-php-pdo

标签

php

function

pdo

while-loop

where-clause