How do I select mysql database in php?

Question

I have this code:

               if(!mysql_connect($host,$user,$passwd)){
                    die("Hoops, error! ".mysql_error());
                }

...no error from here.

                if(!mysql_select_db($db,$connect)){
                    $create_db = "CREATE DATABASE {$db}";
                    mysql_query($create_db,$connect);
                    mysql_query("USE DATABASE {$db}",$connect);
                }

..."no database selected" error from here. I would like to select database if it exists and if doesn't then create it and select it.

Why is my code not right?

Thank you in advance

yes I'm sure about it (its employers), I tried it also without variable and it still didn't work. — Adriana
– Adriana, Commented Feb 12, 2009 at 0:48
Whats with the braces? I haven't worked with mysql/php in ages, but I don't remember that at all. — patricksweeney
– patricksweeney, Commented Feb 12, 2009 at 2:01

PartialOrder · Accepted Answer · 2009-02-12 03:17:33Z

3

Where are you saving the value returned by mysql_connect()? Don't see it here. I assume $host, $user, $password and $db are properly set ahead of time. But you're passing a param to mysql_select_db that may not be properly set.

$connect = mysql_connect($host,$user,$passwd);
if (!$connect) {
    die('Could not connect: ' . mysql_error());
}
if(!mysql_select_db($db,$connect)) ...

Start by checking to see if you can select without the CREATE query first. Try a simple SELECT query to start. If you can connect, select the db, and execute a SELECT query, that's one step. Then try the CREATE query. If that doesn't work, it's almost certainly a matter of permissions.

edited Feb 12, 2009 at 3:17

answered Feb 12, 2009 at 0:38

PartialOrder

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2 Comments

Adriana Over a year ago

My parameters are alright. I've got variable $connect set like you wrote here. Connection is without error, it just doesn't want to select db.I have no idea.Do you?

PartialOrder Over a year ago

Can you perform a simple SELECT query on $db? Leave out the CREATE query to test. Do you get an error? If so, what mysql_errno is returned?

Zak · Accepted Answer · 2009-02-12 00:47:41Z

1

You might need database create permissions for the user attempting to create the database. Then you need to operate on a valid connection resource. $connect never looks to be assigned to the connection resource.

edited Feb 12, 2009 at 0:47

answered Feb 12, 2009 at 0:31

Zak

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1 Comment

Adriana Over a year ago

the same user can create database from command line. I get error "No database selected", nothing more.

Noah · Accepted Answer · 2009-02-12 00:48:09Z

1

Why not simply use the CREATE DATABASE IF NOT EXISTS syntax instead?

Something like this ...

  $con = mysql_connect('localhost');
  $sql = 'CREATE DATABASE IF NOT EXISTS {$db}';
  if (mysql_query($sql, $con)) {
    print("success.\n");
  } else {
    print("Database {$db} creation failed.\n");
  }
  if(!mysql_select_db($db,$connect)){
    print("Database selection failed.\n");
  }

edited Feb 12, 2009 at 0:48

answered Feb 12, 2009 at 0:36

Noah

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2 Comments

Adriana Over a year ago

I tried your code, but the return was failed and failed :(. variable $connect is ok, it doesn't return any error, so I really don't know where is the problem.

staticsan Over a year ago

Sounds like your MySQL user doesn't have enough permissions.

Tom Haigh · Accepted Answer · 2009-02-12 00:43:16Z

0

You should check the return value of mysql_query() - currently if any of those calls fail you won't know about it:

if(!mysql_select_db($db,$connect)){
    if (!mysql_query("CREATE DATABASE $db", $connect)) {
        die(mysql_error());
    }

    if (!mysql_select_db($db, $connect)) {
        die(mysql_error());
    }
}

edited Feb 12, 2009 at 0:43

answered Feb 12, 2009 at 0:32

Tom Haigh

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1 Comment

Adriana Over a year ago

it's so weird, it doesn't report any error. It says "no database selected" only at the point when I want to insert data into table.

Ali · Accepted Answer · 2009-02-12 00:44:45Z

0

Change the line

mysql_query($create_db,$connect);
mysql_query("USE DATABASE {$db}",$connect);

To

mysql_query($create_db,$connect);
mysql_select_db($db);*

and it should work.

answered Feb 12, 2009 at 0:44

Ali

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Comments

roa3 · Accepted Answer · 2009-02-18 06:41:40Z

0

you could try w3schools website. They have a very simple and easy to learn tutorial for selecting database. The link is : http://www.w3schools.com/php/php_mysql_select.asp Hope this help :)

answered Feb 18, 2009 at 6:41

roa3

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Comments

Adriana · Accepted Answer · 2009-02-20 15:26:06Z

0

I would like to thank to all of you, however I found fault on my side. This script was in class and one of variables were not defined inside this class. So I'm really sorry. I don't know how to consider the right answer, but I noticed my mistake after reading Clayton's answer about not properly set parameters, so I guess he is the winner ;)

answered Feb 20, 2009 at 15:26

Adriana

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1 Comment

PartialOrder Over a year ago

@perfectDay The good thing is you got the problem solved. I was beginning to wonder what happened with this one ... Thanks.

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