为什么我会收到绑定参数问题？

Question

This is the error:

Warning: mysqli_stmt_bind_param(): Number of elements in type definition string doesn't match number of bind variables

Let me show you a snippet of code followed by the output.

if (!empty($par_val))
      {
        echo "$sql_update<br>";
        // append par_type with 2 integers for $req_setstatus and $req_activator.
        $par_type .= 'ii';
        echo "$par_type<br>";
        // append par_val with $req_setstatus and $req_activator
        $par_val .= "$req_setstatus,$req_activator";
        echo "$par_val";
        mysqli_stmt_bind_param($stmt,$par_type,$par_val);
      }

here are the outputs:

UPDATE request SET priority = ?,status = ?, activator = ? WHERE id = 35 --> this is the update statement, 3 fields to update.

sii -->this is the $par_type, there are 3 values.

Urgent,2,6 -->this is the $par_val, there are 3 values.

Why am I receiving this error.

I'm thinking that possibly, it is the multiple values being tied into 1 single variable, but if this is the problem, then how would I set this up to take a dynamic set of variables each time it is ran. Sometimes the in inputs can be 3, sometimes 8.

Answer 1

If you need a dynamic amount of parameters, you can use $par_val as an array. So...

$par_val = [2,6];

and then use the array unpacking operator ( ... )...

mysqli_stmt_bind_param($stmt, $par_type, ...$par_val);

You could have $par_val as a csv and use explode() to make it into an array and then unpack it as above...

$par_val = explode(",", "2,6);

Answer 2

I would recommend to use OOP-style, which is easier to read and also use string type ( s ) when you are binding unknown number of parameters. You really don't need to distinguish the integers, and when dynamically binding it makes no difference most of the time whether you bind as string or as integer.

First build and array with your parameters.

$params = [$req_setstatus, $req_activator, $whateverIsYour3rdParam];

Then repeat type s the correct number of times.

$types = str_repeat('s', count($params));

Then bind it. You can use the splat operator (argument unpacking) ... before the array to unpack the array into its constituents.

$stmt->bind_param($types, ...$params);

As an ultimate recommendation, I would advice to use PDO, which is much easier to use. Even better start using a good abstraction library, eg EasyDB.