How to Prevent MySQL Errors Caused by Single Quotes in PHP?

Escaping Single Quotes in PHP for MySQL

You've encountered an issue where a single quote is causing a MySQL error when inserting data into a database. This issue arises when the data is not properly escaped before being inserted.

In the first query, escaping is not necessary because you're inserting data directly from a form. However, the second query retrieves data from a previously inserted record and attempts to insert it into a new table. Since the data may contain unescaped single quotes, it triggers a MySQL error.

To prevent this error, you can use the mysql_real_escape_string() function to escape all strings before inserting them into the database. This function converts special characters like single quotes into their escaped equivalents, preventing them from causing errors.

For example, in Query 2, replace the following line:

<code class="php">$query = mysql_query("INSERT INTO message_log
(order_id, timestamp, message_type, email_from, supplier_id, primary_contact, secondary_contact, subject, message_content, status)
VALUES
('$order_id', '".date('Y-m-d H:i:s', time())."', '$email', '$from', '$row->supplier_id', '$row->primary_email' ,'$row->secondary_email', '$subject', '$message_content', '1')");</code>

With:

<code class="php">$query = mysql_query("INSERT INTO message_log
(order_id, timestamp, message_type, email_from, supplier_id, primary_contact, secondary_contact, subject, message_content, status)
VALUES
('$order_id', '".mysql_real_escape_string(date('Y-m-d H:i:s', time()))."', '".mysql_real_escape_string($email)."', '".mysql_real_escape_string($from)."', '$row->supplier_id', '".mysql_real_escape_string($row->primary_email)."', '".mysql_real_escape_string($row->secondary_email)."', '".mysql_real_escape_string($subject)."', '".mysql_real_escape_string($message_content)."', '1')");</code>

By escaping all strings in this manner, you can prevent single quotes from causing MySQL errors and ensure that data is inserted correctly.

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