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POShould I check a unique constraint with php?
 

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  1. POShould I check a unique constraint with php?
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    <p>Maybe this question has already been asked, but I don't really know how to search for it:</p> <p>I have the postgres-table "customers", and each customer has it's own unique name. In order to achieve this, I added an unique-constraint to this column.</p> <p>I access the table with php.</p> <p>When the user now tries to create a new customer, with a name that has already been taken, the database says "Integrity Constraint Violation", and php throws an error.</p> <p>What I want to do is to show an error in the html-input-field: "Customer-Name already taken" when this happens.</p> <p>My question is how I should do this.</p> <p>Should I catch the PDO-Exception, check if the error-Code is "UNIQUE VIOLATION", and than display a message according to the Exception-Message, or should I check for duplicate names with an additional statement before I even try to insert a new row?</p> <p>What is better practice? Making a further sql-statement, or catching and analyzing error-codes.</p> <p><strong>EDIT:</strong> I'm using transactions, and I'm catching any exception in order to rollback. The question is, if I should filter out Unique-violations so they don't lead to a rollback.</p> <p><strong>EDIT2:</strong> If I'm using the exception-method, I would have to analyse the exception-message in order to ensure that the unique-constraint really belongs to the "name"-column.</p> <p>This is everything I get from the exception:</p> <pre><code>["23505",7,"FEHLER: doppelter Schlüsselwert verletzt Unique-Constraint &lt;customers_name_unique&gt;\nDETAIL: Schlüssel &lt;(name)=(test)&gt; existiert bereits."] </code></pre> <p>The only way to get information about the column is to check if "customers_name_unique" exists (it's the name of the unique-constraint).</p> <p>But as you can also see, the message is in german, so the output depends on the system / might be able to change.</p>
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    1. COMaybe you should look at: http://stackoverflow.com/questions/7719039/php-duplicate-checking-before-insert
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