MySQLi Bind Param Error: Why Does My Number of Type Characters Mismatch My Placeholders?

Bind Param Error: Number Mismatch

In MySQLi prepared statements, the number of type characters (e.g. "s" for string) in the bind_param method must match the number of placeholders (e.g. "?") in the SQL query.

Problem Summary

You are receiving an error because the bind_param call in your code does not match the number of placeholders in the prepared statement:

$stmt->bind_param("s,s,s,s,s,s,s,...", $project_name, $status, ...);

This is likely due to a mismatch between the number of form inputs (65) and the number of placeholders in the query.

Correct Format

The correct format for bind_param is as follows:

$stmt->bind_param("type_characters", $variable1, $variable2, ...);

where "type_characters" is a string containing one character per placeholder in the query, indicating the type of data being bound.

Counting Type Characters

To avoid mismatches, it is recommended to count the number of placeholders manually or using a regular expression. In your case, you should confirm that the prepared statement contains 65 placeholders.

Example

For a modified prepared statement with 65 placeholders, the correct bind_param call would be:

$stmt->bind_param("sssssssssssssssssssssssssssssssssssssssssssssssssssssssss", $project_name, $status, ...);

Tip

To assist in ensuring correct binding, consider using the following method which counts the number of placeholders in a SQL query:

function countPlaceholders($sql) {
  return substr_count($sql, '?');
}

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