PHP says "No Database selected" even after using mysqli_select_db()

Question

I am writing a simple code to fetch 2 elements from a table in my database called Plasma. It seems the connection is being made well but I am unable to select any database due to unknown reason.

Code :

<?php
$db  = "Plasma"; 
$dbH = "localhost";
$dbU = "plasma";
$dbP = "plasma";
      $dbCon = mysqli_connect($dbH,$dbU,$dbP,$db);
        if(!dbCon){
            echo "Conenction Fail";
        }
        mysqli_select_db($dbCon,$db);
        $qry = "select Mid,Mname from ya_movies order by DOA limit 5;";
        $Response = mysqli_query($dbCon,$qry);
        echo mysqli_error($dbCon);                     ?>

The Output is

No database selected

You don't select any database in your code, what happens when you do? — , Jul 02 '13 at 09:50
The character-case matters! Maybe your database is named `plasma` which you are referring to as `Plasma` — amulous, Jul 02 '13 at 09:53
@Your Common Sense Hmm yeah, didn't read that all thoroughly. What happens when you use mysqli_select_db instead of specifying it in mysqli_connect? — , Jul 02 '13 at 09:54
i used mysqli_select_db, sorry that i missed it when i copy pasted the code. — BMC, Jul 02 '13 at 09:55
@BMC such a "miss" *is* a reason for whatever errors you have. — Your Common Sense, Jul 02 '13 at 09:55
What happens when you `select Mid,Mname from Plasma.ya_movies`? — user247702, Jul 02 '13 at 09:57
@YourCommonSense , No the code does contain a mysqli_select_db() which I have updated here. sorry for the confusion. But am still having the issue. — BMC, Jul 02 '13 at 09:57
@Stephan having the same error even after using "USE Plasma" — BMC, Jul 02 '13 at 09:59
Hi @BMC, sorry for seemingly being grumpy and a bit off topic, but (in the spirit of being positively helpful) for the benefit of anyone who has to read your code, I suggest you just use variables $dbHostname and $query - missing out arbitrary characters from strings makes them hard to predict and leads to mistakes (especially in PHP). Also I'd be consistent about the use of case for variable names - either camelCase [recommended for PHP] or PascalCase but not both. — Iain Collins, Jul 02 '13 at 09:59
what does mysqli_error say after running "USE Plasma" query? — Your Common Sense, Jul 02 '13 at 10:03
Yet another long and windy topic spawned by a silly typo... I wish I will learn to spend my life in a more profitable way — Your Common Sense, Jul 02 '13 at 10:07
@YourCommonSense " Access denied for user ''@'localhost' to database 'Plasma'" — BMC, Jul 02 '13 at 10:08
Go on check your credentials first then, and if your variables contain the right values. You don't need no Stack Overflow help for this. — Your Common Sense, Jul 02 '13 at 10:09
@YourCommonSense checking with 'root' user. It's strange that it says "for user ''@'localhost' to" -> the user name is missing — BMC, Jul 02 '13 at 10:10

score 11 · Answer 1 · answered Jul 02 '13 at 10:05

It's a typical case of not enough debug information:

mysqli_select_db($dbCon, $db);

You don't check for the return value; it may return false to indicate it couldn't change the database (probably due to permissions). I would suggest putting this in place and run it:

if (!mysqli_select_db($dbCon, $db)) {
    die("Uh oh, couldn't select database $db");
}

If this happens, double check the name, permissions, etc.

score 2 · Answer 2 · edited Jan 12 '15 at 22:38

2

I can't comment, I dont have the reputation yet, but:

if(!$dbCon){
    echo "Connection Failure!";
}

try this:

if (!$dbCon) {
    die('Connection Error (' . mysqli_connect_errno() . ') '
        . mysqli_connect_error());
}

Might give a more meaningful error message.

edited Jan 12 '15 at 22:38

Lux

1,540
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answered Jul 02 '13 at 10:00

EvilEpidemic

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17

Yes, it's a typo, but it makes no difference because `dbCon` will evaluate to `"dbCon"` making the condition superfluous. – Ja͢ck Jul 02 '13 at 10:02
Tried both with $ and without. – BMC Jul 02 '13 at 10:03

Your Common Sense · Answer 3 · 2013-07-02T10:44:56.123

PHP says “No Database selected” even after using mysqli_select_db()

Nope, it doesn't, if you are using valid credentials.

PHP will set current database all right either way.
The only reason for not to do so is a some sort of typo you made.

You just need to be sure that you actually called this function with proper database name.
And then double-check it. Of course a user have to have rights to access that database.

That's all.
There is no magic.
There is no bug in mysqli.
There is but only one rational explanation. Always trust to your common sense.

A couple of rules you need to learn to avoid such a problem in a future:

In all your further codes ALWAYS make error_reporting(E_ALL); the very first line and never turn it off nor make it less. This way you will be notified of the errors occurred in your code.
Before using database credentials in the code, test them in a console. This way you will make sure that your credentials are proper and works. If have problem with setting proper credentials - as k a question on setting them.
If there are no errors and credentials are all proper - check for the typos in the code.

That's not the only possible reason. It could very well be a permission issue. — user247702, Jul 02 '13 at 10:01

score 0 · Answer 4 · edited Aug 13 '14 at 18:42

0

if(!dbCon){
   echo "Conenction Fail"; 
}

You forgot to add $ in dbCon variable.

edited Aug 13 '14 at 18:42

MH2K9

11,951
7
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answered Aug 13 '14 at 18:37

Rajib BD

1

score -1 · Answer 5 · edited Jul 11 '15 at 12:07

-1

I had the same problem. I created a new database but it could not be selected from PHP. Yet the test database could be selected. I solved it by changing the $user to 'root'. For your case :

$dbU = 'root'

That should work for you.

edited Jul 11 '15 at 12:07

TechWisdom

3,960
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answered Jul 11 '15 at 11:30

Richard Freeman

23
2

This may solve the problem. But a better solution would be to configure the database so it worked with the user specified. – Joe Flynn Jul 11 '15 at 11:56

PHP says "No Database selected" even after using mysqli_select_db()

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