Embedded php loop inside SQL query?

PixelPixie

I want to embed a foreach() loop inside my SQL query as follows:

$query = "UPDATE $table
                SET " . foreach ($_REQUEST as $field => $value) {
                                     echo ("$field='$value'" . ", ");
                            }
                            echo ("$last_key='$last_value'"); .  // popped from array to avoid trailing comma
                         "WHERE student_id = $student_id";

This results in a completely blank page so there is an error in the above code somewhere (page displays properly when above code snippet is commented out), or is what I am trying to do impossible?

The foreach() loop above works perfectly outside the UPDATE statement.

is_that_so

PixelPixie wrote:

I want to embed a foreach() loop inside my SQL query as follows:

$query = "UPDATE $table
                SET " . foreach ($_REQUEST as $field => $value) {
                                     echo ("$field='$value'" . ", ");
                            }
                            echo ("$last_key='$last_value'"); .  // popped from array to avoid trailing comma
                         "WHERE student_id = $student_id";

This results in a completely blank page so there is an error in the above code somewhere (page displays properly when above code snippet is commented out), or is what I am trying to do impossible?

The foreach() loop above works perfectly outside the UPDATE statement.

My first question is why ?

The . notation used here expects either a variable($var .) or a string (eg " string"). You have given it neither.

My suggestion is to populate the rest of the UPDATE outside this and then append it. Then just execute it .
The loop is valid code and works but based on what you have posted you already have the key=> value terms so build it outside.

PixelPixie

is_that_so wrote:

My first question is why ?

The . notation used here expects either a variable($var .) or a string (eg " string"). You have given it neither.

Why? Because I want to read in variables extracted from key-value parirs in array to the SET part of the sql statement. Surely the output values of $field and $value count as strings?

is_that_so wrote:

My suggestion is to populate the rest of the UPDATE outside this and then append it. Then just execute it .
The loop is valid code and works but based on what you have posted you already have the key=> value terms so build it outside.

Thanks for the feedback. I'll do that.