PDO isn't binding PostgreSQL query

Question

I'm using PDO to develop an application with PostgreSQL. The problem is that the binding functions as PDOStatement::bindValue and PDOStatement::bindParam aren't working at all.

I have the following code:

<?php

    try{

        $db = new PDO("pgsql:dbname=test;host=localhost", "user", "password");

        $all = '*';
        $sql = $db->prepare("SELECT :all FROM schema.table");
        $sql->bindValue(':all', $all);

        var_dump($sql->queryString);
        var_dump($sql->execute());

    }

    catch(PDOException $e){
        print $e->getMessage();

    }

?>

I just cannot understand the reason $sql->queryString's value still is SELECT :all FROM schema.table, as it var_dump()'d here.

PDOStatement::bindParam does exactly the same thing.

Any tips?

EDIT: This query is for debugging purposes only! Please, don't care about the query itself but in the method that isn't binding.

Corbin · Accepted Answer · 2013-03-19 06:25:50Z

3

Prepared statements don't work like that. You can only bind values, not entities.

As far as your statement is concerned, you're executing the query SELECT '*' FROM schema.table, Not, SELECT * FROM schema.table

If you want variable entities (which implies a design flaw about 80% of the time), you will have to resort to string interpolation (or concatenation -- you get the point).

answered Mar 19, 2013 at 6:25

Corbin

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8 Comments

Rodrigo Siqueira Over a year ago

Yeah, I know that. I'm using this for debugging purposes. The method should bind it anyway, shouldn't it?

Corbin Over a year ago

@RodrigoSiqueira It will return the string * repeated the number of times that there are rows matched against the query. So yes, it will bind, but it is not what you think it is.

Rodrigo Siqueira Over a year ago

By the execution of $sql->execute(), my code is querying on the database the string SELECT :all FROM schema.table. If the query were SELECT '*' FROM schema.table or SELECT * FROM schema.table, I'd be pretty much happy because it would be working fine.

Corbin Over a year ago

@RodrigoSiqueira Hmm, can you set it so that PDO actually throws exceptions so you can see why it's erroring? (Or you can check errorCode or errorInfo)

Craig Ringer Over a year ago

@Corbin PDO's failure to throw exceptions by default seems to cause so much confusion. Very frustrating that it can't be changed because of BC.

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