How to Resolve PDO Error \'General Error: 2031\' in PHP?

Error Trapping for PDO's "General Error: 2031"

When encountering the PDO error "SQLSTATE[HY000]: General error: 2031," it's crucial to consider the underlying cause. This error often arises when using placeholders (:placeholder) in queries and manually binding values to them with bindValue().

While the error message doesn't always indicate an invalid number of parameters, it's vital to ensure that all placeholders have been bound correctly. In the provided code snippet, the query contains two LIMIT placeholders, which are manually bound to :page and :entries_per_page.

However, it's essential to note that binding two values to the same parameter name can also trigger error 2031. For instance, mistakenly using bindValue to bind two different colors to the ':colour' parameter, as shown below, can lead to this error:

<code class="php">$sth->bindValue(':colour', 'blue');
$sth->bindValue(':colour', 'red');</code>

Therefore, when using bindValue to assign values to placeholders for LIMIT clauses or other purposes, it's imperative to ensure that the parameter names are unique. By adhering to this practice, developers can avoid the annoyance of encountering error 2031 and maintain clean and efficient code.

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