Why does this SQL query result in an undefined index error?

Question

I am trying to understand why I get this error:

Notice: Undefined index: id in E:\xampp\htdocs\CVToolGismo\addCV.php on line 472

The part of the code that I get the error is this:

if($query = mysql_query("SELECT job_title,company,website,start_date,end_date,start_year,end_year,work_history FROM work WHERE username='$username' order by id asc limit 1") or die(mysql_error())){
                  if(mysql_num_rows($query)>0){
                    while($row = mysql_fetch_array($query)) {
                         $id = $row['id'];
                    }
                  }
                  else{
                      echo '<script>ErrorMessage()</script>';
                  }
              }

Because you’re not selecting a column named `id` in your statement …? — CBroe, Mar 12 '15 at 22:12
This is not a duplicate of that question. I'm sure it's a duplicate of *some* question, but not *that* one. — Ignacio Vazquez-Abrams, Mar 12 '15 at 22:19
@IgnacioVazquez-Abrams Please tell me why this should not be a dupe?! He wants to access an undefined index in an array, from my perspective this is an exact dupe — Rizier123, Mar 12 '15 at 22:22
@Rizier123: That question covers the general case of the index not existing. The issue in this question is that the asker has deliberately crafted their code (and specifically their SQL query) to invoke the error. — Ignacio Vazquez-Abrams, Mar 12 '15 at 22:26
@IgnacioVazquez-Abrams But don't you think with a little debugging and the use of google he would have spotted that? Also *I'm sure it's a duplicate of some question* If you know about a dupe which I'm not aware of, why do you answer a duplicate question? — Rizier123, Mar 12 '15 at 22:28

score 1 · Answer 1 · answered Mar 12 '15 at 22:12

1

Your query doesn't have a id column.

answered Mar 12 '15 at 22:12

Ignacio Vazquez-Abrams

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if I place the id and make my select like this ... "SELECT job_title,company,website,start_date,end_date,start_year,end_year,work_history FROM work WHERE id>'$id' AND username='$username' order by id asc limit 1" ... I am still getting this error :/ – Waaaaat Mar 12 '15 at 22:17
1

That query still doesn't have a `id` column. – Ignacio Vazquez-Abrams Mar 12 '15 at 22:17
After the WHERE I have this id>'$id' – Waaaaat Mar 12 '15 at 22:18
That's a criterion, not a column. – Ignacio Vazquez-Abrams Mar 12 '15 at 22:19

score 1 · Answer 2 · answered Mar 12 '15 at 22:15

1

In your query you haven't actually selected the id column. You must query the id column in the SELECT statement to use it.

answered Mar 12 '15 at 22:15

Ben Butler

11
2

Why does this SQL query result in an undefined index error?

2 Answers2