How to compare the data from form and need to fetch another data from database in PHP

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I need to compare the dates in the form that the later dates should not be earlier than the first one and this is works when I use Javascript. However, I need to compare another field(num_file_ptj) from the form with the database if its already existed and I'm kind of clueless on this since the form already have onsubmit function.

What I have tried:

I comment out the onsubmit function on the form and use PHP script but it seems the data wont enter the database

Posted 8-Jun-24 18:41pm

Member 16279690

Updated 8-Jun-24 22:00pm

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Pete O'Hanlon · Answer 1 · 2024-06-08T21:54:00

Solution 1

If that column can only ever have one record with a certain value in it, make the column unique in your table. When you execute the insert statement, you will get an error code if the value is a duplicate.

I can't tell you what that error will be because I have no idea what database you are using.

Posted 8-Jun-24 21:54pm

Pete O'Hanlon

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Member 16279690 9-Jun-24 4:24am

I am using MySQL database. Not sure if MySQL can execute error if the value is duplicate. If I put the duplicate value on the unique column on the form, after clicking the submit button, the page return blank. I'm still newbie on this

Pete O'Hanlon 9-Jun-24 4:33am

You get error code 1062 back. Check the error immediately after you make the insert statement and you should be good to go. You need something like

if (mysqli_error() == 1062){ tell the user there was a duplicate }

Note, you should use define a constant rather than use the magic number of 1062.

Member 16279690 9-Jun-24 4:52am

Seems like didn't work from my end :( Not sure if I was getting error code 1062 cause when I inspect the browser, it only shows have 1 issue
The script is like this:
// Finally add to registration table
$stmt = mysqli_prepare($connection, "INSERT INTO tblapplication (no_file,no_file_md,no_file_ptj,client_name,client_phone,client_email,ptj_id,status) VALUES (?,?,?,?,?,
(SELECT tblptj.ptj_id FROM tblptj WHERE tblptj.reg_date=? AND tblptj.pass_date=? AND tblptj.ljt_pay=? AND tblptj.ljt_certificate=? AND tblptj.qt_reg=? AND tblptj.qt_pass=?),?);");

mysqli_stmt_bind_param($stmt, 'sssssssssssss', $_POST["no_file"],$_POST["no_file_md"],$_POST["no_file_ptj"],$_POST["client_name"],$_POST["client_phone"],$_POST["client_email"]
,$_POST["reg_date"],$_POST["pass_date"],$_POST["ljt_pay"],$_POST["ljt_certificate"],$_POST["qt_reg"],$_POST["qt_pass"]
,$_POST["status"]);
/* execute prepared statement */
mysqli_stmt_execute($stmt);

/* close statement and connection */
mysqli_stmt_close($stmt);

if (mysqli_error() == 1062){
$msg = "
Please check your email!
";
}

The form is still using onsubmit function which check the dates. For email or any unique column, not sure how to execute the error

Pete O'Hanlon 9-Jun-24 5:41am

Your error handling is attempting to check the result of closing the connection, not executing the insert.