Can PDO Prepared Statements Reuse Named Placeholders?

PDO Prepared Statements: Reusing Named Placeholders

When working with PDO, it may be desirable to reuse named placeholders in a prepared SQL query. However, this is not possible due to the limitations of PHP's PDO::prepare function.

As per the PDO documentation, "you cannot use a named parameter marker of the same name twice in a prepared statement." This means that if you attempt to use the same named placeholder multiple times in your query, such as:

SELECT :Param FROM Table WHERE Column = :Param

...the second occurrence of the ":Param" placeholder will be replaced with a unique placeholder name by the PDO::prepare function. When you bind your value to the ":Param" placeholder using PDO::bindValue(":Param"), it will only set the value for the first occurrence of the placeholder. The second occurrence will remain unbound, leading to an error when you execute the query.

Therefore, it is not possible to reuse named placeholders in a prepared SQL query using PDO. If you need to repeat the same value multiple times in your query, you can either use positional placeholders (e.g. "?", ":1", etc.) or create multiple prepared statements with different placeholder names.

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