Put all indexs of array in a comma separated string [closed]

Question

I have an array that looks like this:

array('first' => 'value1', 'second' => 'value2', ...);

How can I get all the keys and put them in a comma separated string?

At the very end I need something like this, to do a query:

values IN ('first','second',...)

Thanks

Answer 1

should be enough:

echo "'".implode("','", array_keys($array))."'";