Selecting one value from database?

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+--- Thread: Selecting one value from database? (/showthread.php?tid=3792)

Selecting one value from database? - El Forum - 10-22-2007

[eluser]fancms[/eluser]
I need to select one value from one row in the database. With the database class I used previously before finding CI I could accomplish this by doing

Code:
$variable = $db->get_var("SELECT somevalue FROM sometable WHERE something='therowvalue'");

This would allow me to use $variable as-is throughout my code.

I've been trying to figure out how to do this (select one value from a table) in CI. Right now I have

Code:
$this->db->select('value'); #Because I need the value

$this->db->where('variable', 'siteoverview'); #Because I need the variable column entitled siteoverview

$grab_cache = $this->db->get("settings"); #From the settings table

This produces

Code:
CI_DB_mysql_result Object

(

    [conn_id] => Resource id #27

    [result_id] => Resource id #31

    [result_array] => Array

        (

        )

    [result_object] => Array

        (

        )

    [current_row] => 0

    [num_rows] => 1

)

I'm a bit lost here. I haven't been able to find my answer in the docs, the forums, or the wiki. I know this is a basic question (and I'll likely feel pretty dumb when I find/get the answer) but I'm hoping someone will be kind enough to clarify a bit.

Thanks! Smile

Selecting one value from database? - El Forum - 10-22-2007

[eluser]ELRafael[/eluser]

Code:
$tabela = 'usuarios';

$this->db->select('nome');  //Will find 'Rafael', my name

$this->b->where('cidade', 'São Bernardo do Campo'); //Where user in my city

$query = $this->get($tabela); // Get this f&#xck; name!

$nome = $this->db->row();

$nome = $nome->nome;

echo $nome //Produces Rafael

Capisce fancms?

It's a ugly example, but i hope you understand :-P

Selecting one value from database? - El Forum - 10-22-2007

[eluser]xwero[/eluser]
[quote author="fancms" date="1193079984"]

Code:
$this->db->select('value'); #Because I need the value

$this->db->where('variable', 'siteoverview'); #Because I need the variable column entitled siteoverview

$grab_cache = $this->db->get("settings"); #From the settings table

[/quote]

You are on the right path but you have to go more specific

Code:
$this->db->select('value'); #Because I need the value

$this->db->where('variable', 'siteoverview'); #Because I need the variable column entitled siteoverview

$query = $this->db->get("settings"); #From the settings table

$row = $query->row; // get the row

echo $row->value

If you want to put it in a function

Code:
function scalar($table,$field,$where)

   $this->db->select($field); #Because I need the value

   $this->db->where($where); #Because I need the variable column    entitled siteoverview

   $query = $this->db->get($table); #From the settings table

   $row = $query->row_array(); // get the row

   return $row[$field]; // return the value

}

Selecting one value from database? - El Forum - 10-22-2007

[eluser]fancms[/eluser]
Thank you both, Rafael and xwero; it makes a lot more sense now Smile

One more question - since this is a function I'd definitely want to reuse, is it something I could make into a plugin / helper? How would I go about running the database queries from an external function file like that? When I tried saving it as a plugin, loading it in the controller file, and running the function, I got the message:

Quote:Fatal error: Using $this when not in object context

Selecting one value from database? - El Forum - 10-22-2007

[eluser]Armchair Samurai[/eluser]
If you're going to use CI resources (like the DB class) in your custom libraries, helpers and plug-ins, you need to use the get_instance() function.

Check the Creating Libraries section in the User Guide.

Selecting one value from database? - El Forum - 10-22-2007

[eluser]xwero[/eluser]
If you want to use it as a function you can extend the model library, name the file MY_Model and put it in the application/libraries directory and add following code

Code:
class MY_Model extends Model {

    function My_Model()

    {

        parent::Model();

    }

    function scalar($table,$field,$where)

    {

       $this->db->select($field);

       $this->db->where($where);

       $query = $this->db->get($table);

       $row = $query->row_array();

       return $row[$field];

    } 

}

This way you don't have to load it yourself and you can use $this->scalar() to call the function.

Selecting one value from database? - El Forum - 10-22-2007

[eluser]fancms[/eluser]
Great! Thanks so much for your help! Smile