Sending message back if table row has value

Question

For example, have a query like this:

<?php
$sql  = "INSERT INTO oppgave    
    (username, besvarelse, modulid) 
    VALUES
    ('$username', '$besvarelse', '$modulid');
    ";

    mysql_query($sql, $tilkobling);
?>

How can I do this:

If modulid row is not empty, echo "you have sent this modul before";

are you trying to check where that particular row already exists before inserting into the database? — user1978142, Apr 29 '14 at 08:18
to know if a field is empty or not refer to this link : http://stackoverflow.com/questions/8470813/how-do-i-check-if-a-column-is-empty-or-null-in-mysql — daR, Apr 29 '14 at 08:21
the row modul id contain values from 1-6. if a user try input a value who alredy exist i want the user to get the message back that it already exist — user2879767, Apr 29 '14 at 08:21

Ravi Dhoriya ツ · Accepted Answer · 2014-04-29T08:39:19.033

2

Try this:

<?php
$sql  = "INSERT INTO oppgave(username, besvarelse, modulid) 
         select '$username', '$besvarelse', '$modulid'
         from dual
         where not exists (select modulid from oppgave where modulid='$modulid')";

$result=mysql_query($sql, $tilkobling);
if(mysql_affected_rows()==0){
      echo "Failed to insert duplicate modulid";
}else{
      echo "inserted";
}
?>

In this SQL Query, it will allow insert only if $modulid isn't already exist in database table. Such situation you can also handle by applying UNIQUE constraint to table column (but remember, it allows NULL value at once)

edited Apr 29 '14 at 08:39

answered Apr 29 '14 at 08:22

Ravi Dhoriya ツ

4,435
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I think this is what i need Log1c, but getting this : Parse error: syntax error, unexpected '<' in – user2879767 Apr 29 '14 at 08:29
Did u forgot to close `?>` ? – Ravi Dhoriya ツ Apr 29 '14 at 08:30
1

I think you already have The "" Tag. Remove those from Log1c's answer – Nick Prozee Apr 29 '14 at 08:33
i'll get the data inserted eveytime :( – user2879767 Apr 29 '14 at 08:39
i have set modulid row as unique, do the data is not overwrited – user2879767 Apr 29 '14 at 08:40
@user2879767, Can i know the reason why you un-accepted my answer? It was correct as per your requirement specified *in the question*. – Ravi Dhoriya ツ Apr 30 '14 at 06:02

score 1 · Answer 2 · answered Apr 29 '14 at 08:24

1

Best way to do this, is by not allowing duplicates.
You can do this with your SQL QUERY.

Build your query by this:

 $sqlString ="INSERT INTO oppgave('" . $username . "', '" . $besvarelse . "', '" . $modulid . "')
    SELECT username, besvarelse, modulid
    FROM oppgave
    WHERE NOT EXISTS (SELECT *
                      FROM oppgave
                      WHERE modulid IS NULL)";

Please check all names and tablenames first ;)
Hope this helps.

If this the answer, please mark as answer.

answered Apr 29 '14 at 08:24

Nick Prozee

2,823
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But i think this isn't real answer to the question, as OP wants to *insert rows only if modulid isn't already exist in table* but here **your query won't allow duplicate rows (instead of just one column)**. Isn't it? – Ravi Dhoriya ツ Apr 29 '14 at 08:58

Sending message back if table row has value

2 Answers2