Check Whether a Table Exists

This is a quick tip. It isn’t usually an issue with MODX tables, but if you create custom database tables in the MODX database, you may eventually need some code to determine whether a table exists or not.

You might have code that creates the table, but shouldn’t run if the table already exists, or code that modifies a table, but shouldn’t execute if the table doesn’t exist.

Here’s a quick and easy way to do that in MODX:

$table = "full_table_name";
$tableExists = gettype($modx->exec("SELECT count(*) FROM $table")) == 'integer';

if ($tableExists) {
    echo "YES";
} else {
    echo "NO";
}

The technique rests on the interesting fact that the $modx variable is also a database handle. This results from the fact that the modX class extends the xPDO class, which maintains a permanent connection to the MODX database.

Note that the $table variable must contain the full name of the actual table (including its prefix).

This technique will work regardless of whether the table is empty or not. As long as the table exists, the $tableExists variable will be true.

Suppose that you know the class name, but you can’t remember the name of the table. If the class is set up to work with xPDO, you can get the table name from MODX like this:

$tableName = $modx->getTableName('modResource');

The table name returned from the code above will include the table prefix and will be surrounded by backticks. So the result of the call will be (assuming that your table prefix is modx_):

`modx_site_content`

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Bob Ray is the author of the MODX: The Official Guide and dozens of MODX Extras including QuickEmail, NewsPublisher, SiteCheck, GoRevo, Personalize, EZfaq, MyComponent and many more. His website is Bob’s Guides. It not only includes a plethora of MODX tutorials but there are some really great bread recipes there, as well.