How to return a constant or a text string in PHP -- is eval() the way to go

I have a row in a mysql table whose column contains:

This is a test.

I have another row in the same mysql table whose same column contains:

K_IM_A_CONSTANT

Earlier on in the PHP script, this line of code exists:

define(K_IM_A_CONSTANT, 'This is a constant.');

How 开发者_Go百科can I echo the contents of the column whereby, the returned value would either be "This is a test." or "This is a constant.", depending on the row selected?

Is eval() the way to do it? If so, how might the eval() syntax look? I have been getting too many errors trying to get eval() to work.

Thanks for helping.

Use the constant function:

if(defined($row['column_name']))
{
    echo constant($row['column_name']);
}

So given a piece of text, you want to find the name of a constant whose value matches the piece of text? This seems like a hideous abuse of "constants" to me, but, you'd want to use get_defined_constants():

function find_constant_name($text) {
    $constants = get_defined_constants();
    foreach($constants as $const => $val) {
        if ($val == 'Your specified text') {
             return($const);
        }
    }
}

find_constant_name('This is a test.');