Check if record already exists in database

Question

Possible Duplicate:
insert contacts into database but does not want to duplicate already existing contact

Hello. I'm trying to check if an email already exists before I insert a duplicate.

So I need to check the database for the presence of the email address and if it exists ouput a message saying it already exists. Otherwise I want to insert the record into the database.

Here is the code I use to insert the email now, but I'm not sure how to check the database for existence.

$addEmailQuery  = sprintf("INSERT INTO `subscribe`(`Email`) VALUES('%s')",
                            mysql_real_escape_string($_POST['inputEmail']));
        $addEmailResult = mysql_query($addEmailQuery);
        if($addEmailResult){
            echo 'Email successfully submitted';

        } else{
            echo 'Sorry, we could not submit your email. Please try again.';
        }

Anyone know how I would do this?

yes check if it already exists. If so echo it already exists in db. else insert the email entered in form. — user921334, Sep 06 '11 at 11:04

score 0 · Answer 1 · answered Sep 06 '11 at 11:05

Do a SELECT before your Insert and check if a value is returned for this email. Thats the simplest way to do it.

$CheckEmailQuery  = sprintf("SELECT `Email` FROM `subscribe` WHERE `Email` = '%s'",
                        mysql_real_escape_string($_POST['inputEmail']));
    $CheckEmailResult = mysql_query($CheckEmailQuery);
    if($CheckEmailResult){
        // Do What you are doing above
    }

I have just given the idea but not tested it.

score -1 · Accepted Answer · edited May 23 '17 at 12:04

-1

EDITED: The initial answer will pose problems in a multi-user environment.

You should do like

INSERT ... ON DUPLICATE KEY UPDATE

Follow this answer to get it correct.

ORIGINAL POST:

if(mysql_num_rows(mysql_query("SELECT * FROM subscribe WHERE Email = '".mysql_real_escape_string($_POST['inputEmail'])."'")))
{
     echo "already submitted";
}   
else
{

    $addEmailQuery  = sprintf("INSERT INTO `subscribe`(`Email`) VALUES('%s')",
                        mysql_real_escape_string($_POST['inputEmail']));
    $addEmailResult = mysql_query($addEmailQuery);
    if($addEmailResult)
    {
       echo 'Email successfully submitted';

     } 
     else
     {
        echo 'Sorry, we could not submit your email. Please try again.';
     }

}

edited May 23 '17 at 12:04

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1

answered Sep 06 '11 at 11:06

Mithun Satheesh

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It will fail in a multi user environment - another user can insert between the select and your insert – mmmmmm Jan 18 '13 at 12:19
@Mark: please suggest a solution then.. – Mithun Satheesh Jan 18 '13 at 12:24
1

@mithunsatheesh for mysql see [this question](http://stackoverflow.com/questions/1218905/how-do-i-update-if-exists-insert-if-not-aka-upsert-or-merge-in-mysql) – mmmmmm Jan 18 '13 at 12:26
@Mark: thanks brother.. that helps.. also if you can, just edit this answer to make it correct.. may help others – Mithun Satheesh Jan 18 '13 at 14:08

Check if record already exists in database

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