Lookups in PHP

[RynMan]

Hey guys

If anyone here has ever used VBA or Access....I'm wondering if there is a PHP equivalent of the DLookup? Basically it's a nice little function that returns the value of a field, given specific criteria. I guess you could do the same thing by running a query and using the WHERE condition, but was wondering if there is a simple PHP function that will do it for you?

[jwagner]

Can you please provide an examply of how dlookup() is used in VB?

I'm sure it would be pretty easy building a custom function doing the same thing, using MySql in the function and passing some parameters to it.

[RynMan]

jwagner;10919483 wrote:

Can you please provide an examply of how dlookup() is used in VB?

I'm sure it would be pretty easy building a custom function doing the same thing, using MySql in the function and passing some parameters to it.

Sure.

Dlookup( [FieldName], [TableName], [Criteria])

So if I wanted to pull back the height (from the field 'Height') of a person who had ID #88 from the tblPersonDetails table, I'd do....

Dlookup( "Height", "tblPersonDetails", "[ID] = 88")

So in other words I guess it's just a shorter way of writing....

SELECT tblPersonDetails.Height
FROM tblPersonDetails
WHERE [ID] = 88;

[NogDog]

I suppose you could do something like this if you wanted to (untested):

<?php
/**
 * Get one column from one row in one table via basic MySQL functions
 * @param string $table
 * @param string $column
 * @param string $keyColumn
 * @param string $keyValue
 * @return string 
 */
function dbLookup($table, $column, $keyColumn, $keyValue)
{
   if(!is_numeric($keyValue))
   {
      $keyValue = "'".mysql_real_escape_string($keyValue)."'";
   }
   $query = "SELECT `$column` FROM `$table` WHERE `$keyColumn` = $keyValue";
   $result = mysql_query($query);
   if($result == false)
   {
      $return = false;
      user_error(mysql_error());
   }
   elseif(mysql_num_rows($result) == 0)
   {
      $return = false;
      user_error("no rows returned by query");
   }
   else
   {
      $return = mysql_result(0);
   }
   return $result;
}
?>

Generally though I have my DB stuff down in model-type classes, and I've never really felt any need for such a generic function.

[RynMan]

NogDog;10919496 wrote:

Generally though I have my DB stuff down in model-type classes, and I've never really felt any need for such a generic function.

Forgive my novice-ness (word?), but can you explain what you mean by having it down in model-type classes? What are classes?

[jwagner]

NogDog;10919496 wrote:

I suppose you could do something like this if you wanted to (untested):

<?php
/**
 * Get one column from one row in one table via basic MySQL functions
 * @param string $table
 * @param string $column
 * @param string $keyColumn
 * @param string $keyValue
 * @return string 
 */
function dbLookup($table, $column, $keyColumn, $keyValue)
{
   if(!is_numeric($keyValue))
   {
      $keyValue = "'".mysql_real_escape_string($keyValue)."'";
   }
   $query = "SELECT `$column` FROM `$table` WHERE `$keyColumn` = $keyValue";
   $result = mysql_query($query);
   if($result == false)
   {
      $return = false;
      user_error(mysql_error());
   }
   elseif(mysql_num_rows($result) == 0)
   {
      $return = false;
      user_error("no rows returned by query");
   }
   else
   {
      $return = mysql_result(0);
   }
   return $result;
}
?>

Generally though I have my DB stuff down in model-type classes, and I've never really felt any need for such a generic function.

If you really want to mimc the function you are used to you can pass one string value and divite it at the equals sign.

[NogDog]

RynMan;10919497 wrote:

Forgive my novice-ness (word?), but can you explain what you mean by having it down in model-type classes? What are classes?

I was thinking of "model" in terms of what is referred to as the model/view/controller (MVC) design concept, where a "model" is a class which is used to, among other things, access the data for a thing being modeled. In retrospect I don't think that it really has any specific bearing on my response, though: regardless of how I design my scripts, I cannot really think of many (if any) situations where I wanted/needed to grab just one column from one row of one database table without also accessing other tables, columns and/or rows. In those cases, it would be very inefficient to generate a separate query for each table/column/row needed when it could all be done in a single query whose result set is then further processed by the application code.