HY093 usually means the SQL placeholders and bound values do not match. The fastest fix is to compare the final SQL contract, not stare at the exception.
PDO uses placeholders so SQL and values can be handled separately. HY093 often appears when the query contains a different number or set of placeholders than the values supplied to execute(), or when a named placeholder is missing, misspelled or reused in a way the driver does not support.
The error may surface far away from where the query string was built, especially when filters are assembled dynamically.
Log or inspect the final SQL with sensitive values excluded. For positional placeholders, count every question mark and compare it with the parameter array. For named placeholders, list the unique names and compare them with the bound keys.
A common bug is adding a WHERE clause conditionally but forgetting to add the corresponding parameter, or adding the parameter even when the condition was not added.
One placeholder does not automatically expand to an array. `WHERE id IN (?)` with an array value is not equivalent to several placeholders. Generate the correct number of placeholders and merge the values into the final parameter list.
Wrap query-building logic in small functions and test combinations of optional filters so placeholder mismatches are caught before production.
Avoid mixing named and positional placeholders in the same statement. Consistency makes dynamic SQL easier to reason about. If a query is complex enough that parameter management becomes fragile, a query builder can help — but understanding the final SQL remains essential.