PHP MYSQL query - Strip away columns from response

Question

Is it possible to strip away columns from the response I get in a query where I join 3 tables and need more or less all columns for the query itself so that some columns aren't visible in the response?

This is the query I have:

    $sth = mysql_query("
        SELECT
            tbl_subApp2Tag.*,
            tbl_subApp.*,
            tbl_tag.*
            ISNULL(tbl_userDeviceNOTTag.userDevice_id) AS selected

        FROM tbl_subApp2Tag

        LEFT JOIN tbl_subApp
            ON tbl_subApp.id = tbl_subApp2Tag.subApp_id
            AND tbl_subApp.subApp_id = '".$sub."'

        LEFT JOIN tbl_tag
            ON tbl_tag.id = tbl_subApp2Tag.tag_id

        LEFT JOIN tbl_userDeviceNOTTag
            ON tbl_userDeviceNOTTag.tag_id = tbl_tag.id
            AND tbl_userDeviceNOTTag.userDevice_id = '".$user."'

        WHERE tbl_subApp2Tag.subApp_id = tbl_subApp.id

        ORDER BY tbl_tag.name ASC ");
    if(!$sth) echo "Error in query: ".mysql_error();
    while($r = mysql_fetch_assoc($sth)) {
        $rows[] = $r;
    }

This can help if I got you right stackoverflow.com/questions/9122/… — Narek
– Narek, Commented Feb 29, 2012 at 8:43
Which columns do you need? Basically, you only need to include the columns you want in to SELECT. You don't need to include them into SELECT just to use them in JOINs or as WHERE clause. — Martin Rothenberger
– Martin Rothenberger, Commented Feb 29, 2012 at 8:45
Best way to do this is by explicitly specifying the columns you need. — Salman Arshad
– Salman Arshad, Commented Feb 29, 2012 at 8:50

Philip Sheard · Accepted Answer · 2012-02-29 08:47:40Z

2

You do not need to include columns in the result table, just because they are referenced elsewhere in the query. Just select the columns that you need.

answered Feb 29, 2012 at 8:47

Philip Sheard

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3 Comments

just_user Over a year ago

Do you mean in SELECT? I've tried this, for example I changed the tbl_subapp.* to tbl_subapp.id which the results in an error in the query! Error in query: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near 'ISNULL(tbl_userDeviceNOTTag.userDevice_id) AS selected FROM tbl_subApp2Tag' at line 5<br /> <b>Warning</b>: mysql_fetch_assoc(): supplied argument is not a valid MySQL result resource in

Philip Sheard Over a year ago

It is probably an error in the syntax. I have just noticed that you are missing a comma from your original query.

just_user Over a year ago

Thanks man, that did it. Missing the comma caused the error, so with your suggestion it worked perfectly! Thanks!

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