Notice: Undefined index: Ans in C:\wamp64\www\quiz\remove\repeated.php on line 13

Question

How to resolve this?

Notice: Undefined index: Ans in C:\wamp64\www\quiz\remove\repeated.php on line 13

My code:

require_once '../class.user.php';
$user_home = new USER();
$lstmtf = $user_home->runQuery("SELECT COUNT(Ans)
FROM answer AS a
LEFT JOIN students_records AS s ON a.Sr = s.Sr
WHERE s.Sr IS NULL");
    $lstmtf->execute();
$reg_rst = $lstmtf->fetch(PDO::FETCH_ASSOC);
$registered= $reg_rst['Ans'];
        echo $registered;

My table answer has column name Ans.

Actually, I want to count the numbers of rows which do not have values in students_records.

For Eg:

students_records

+----+-----+-----+ 
| Sr | SRN | ARN |
+----+-----+-----+
| 1  | ge  | aj  |
| 2  | ge  | bd  |
+----+-----+-----+

answer

+----+-----+-----+
| Sr | SRN | ARN |
+----+-----+-----+
| 1  | ge  | aj  |
| 2  | ge  | aj  |
| 3  | ge  | ne  |
| 4  | ge  | bd  |
+----+-----+-----+

Here count should be 1. As the value "ne" in column ARN of table answer is no where in the rows of column ARN in table students_records.

Possible duplicate of [PHP: "Notice: Undefined variable", "Notice: Undefined index", and "Notice: Undefined offset"](https://stackoverflow.com/questions/4261133/php-notice-undefined-variable-notice-undefined-index-and-notice-undef) — Jens, Nov 23 '17 at 11:13
@urfusion if I write `COUNT(Ans) as Ans` it gives me the result, but it counts all row. But I want to count only rows which do not have value in table `students_records` — PB Musics, Nov 23 '17 at 11:17
CAn you create your tables on http://sqlfiddle.com and share it in your question. — urfusion, Nov 23 '17 at 11:31
@urfusion [Somehow like this?](http://sqlfiddle.com/#!9/c07fd0/1) — PB Musics, Nov 23 '17 at 11:40
try this `SELECT a.* FROM answer AS a LEFT JOIN students_records AS s ON a.ARN = s.ARN WHERE s.ARN IS NULL` — urfusion, Nov 23 '17 at 12:05

score 1 · Answer 1 · answered Nov 23 '17 at 11:12

1

Use like this

$lstmtf = $user_home->runQuery("SELECT COUNT(Ans) as Ans
FROM answer AS a
LEFT JOIN students_records AS s ON a.Sr = s.Sr
WHERE s.Sr IS NULL");

answered Nov 23 '17 at 11:12

Himanshu Upadhyay

6,558
1
20
33

Can you please look at https://stackoverflow.com/questions/47454098/notice-undefined-index-ans-in-c-wamp64-www-quiz-remove-repeated-php-on-line-1#comment81862902_47454098 – PB Musics Nov 23 '17 at 11:18

urfusion · Accepted Answer · 2017-11-23T12:56:32.023

0

You can get the desire output by following

SELECT count(a.Ans) as ans
FROM answer AS a
LEFT JOIN students_records AS s ON a.ARN = s.ARN
WHERE   s.ARN IS NULL

Here is working example

edited Nov 23 '17 at 12:56

answered Nov 23 '17 at 12:08

urfusion

5,528
5
50
87

If I want to delete all those rows from the answer, what will be the code? can you please edit your answer and add more code which works for deletion... A request. – PB Musics Nov 23 '17 at 17:33
Can you please help me with it. – PB Musics Nov 24 '17 at 09:41
You want to do that in 1 query or can write another query after getting results? – urfusion Nov 24 '17 at 10:02
I want to delete all that queries, meaning if there are 5 all 5 should be deleted! – PB Musics Nov 24 '17 at 10:04
`DELETE a FROM answer AS a LEFT JOIN students_records AS s ON a.ARN = s.ARN WHERE s.ARN IS NULL` – urfusion Nov 24 '17 at 10:14
@PBMusics : check the query. – urfusion Nov 24 '17 at 10:22
Yes, looked and I will try to execute it as I get time, thanks a lot – PB Musics Nov 24 '17 at 10:24
Sorry to disturb can you please have a look at this: https://stackoverflow.com/questions/47485738/how-do-i-remove-pma-tables-from-mysql-without-affecting-other-tables – PB Musics Nov 25 '17 at 12:11

Notice: Undefined index: Ans in C:\wamp64\www\quiz\remove\repeated.php on line 13

2 Answers2