RE: [PHP] Doubts concerning a general Insert method
Ok... according to the above posts, I've started to create my generic CRUD class however, I'm wondering: Any of you have already used a DAO design pattern in conjunction with a CRUD generic class? Know that I'm trying to create a generic CRUD class on a DAO Design pattern, it seems that it makes no sense at all. Is there an advantage on doing this? My thought: On a insert to database scenario for example: Without the CRUD generic class: to do an insert, we instantiate a DAO class and then call the insert method. Nothing more. Done. With the CRUD generic class: maybe we will have less code on the DAO site but, at the end, to insert a record, we still need to instantiate a DAO and call a insert method SO... I see not big advantage on using both... Can I have your advice on this please? Thanks, Márcio -- PHP General Mailing List (http://www.php.net/) To unsubscribe, visit: http://www.php.net/unsub.php
[PHP] Doubts concerning a general Insert method
Hello, I'm trying to understand a general CRUD class that I've seen here:
http://www.phpro.org/classes/PDO-CRUD.html
I'm learning PHP and I have some doubts on this method to generally insert
data into DB. The class name is crud and here is the method:
public function dbInsert($table, $values) {
$this-conn();
$fieldnames = array_keys($values[0]);
$size = sizeof($fieldnames);
$i=1;
//construction of the prepared statment
$sql = INSERT INTO $table;
$fields = '( ' . implode(' ,', $fieldnames) . ' )';
$bound = '(:' . implode(', :', $fieldnames) . ' )';
$sql .= $fields.' VALUES '.$bound;
//prepares statement e saves it on variable $stmt
$stmt = $this-db-prepare($sql);
foreach($values as vals)
{
$stmt-execute($vals);
}
}
To place values on the DB we do:
$crud = new crud();
$values = array
(
array('animal_name'='bruce', 'animal_type'='dingo'),
array('animal_name'='bruce', 'animal_type'='kangaroo'),
);
$crud-dbInsert('animals', $values);
The doubts:
1) Names convention question:
Isn't more correct to call $columname, instead of $fieldname ?
2) Why do we have this?
$i=1
3) Here:
$fieldnames = array_keys($values[0]);
We are keeping on variable $fieldnames, the key value of the $values array,
when this array is on the position 0 ? And what is *actually* the value
returned, considering our array?
$values = array
(
array('animal_name'='bruce', 'animal_type'='dingo'),
array('animal_name'='bruce', 'animal_type'='kangaroo'),
);
4) Here:
foreach($values as $vals)
{
$stmt-execute($vals);
}
We are telling that, for each (line/element/index ???) of $values array, the
actual value will be given(?) to vals, and the pointer goes to the next
(line/element/index)... ?
We then execute the prepared statement, but I don't get what are we passing
as a param? I mean, what kind of think does the execute PDO method expects
as a param?
Why $stmt-execute($vals); and not only $stmt-execute(); ?
Can I please have your help on clarifying those doubts?
Thanks a lot,
Márcio
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Re: [PHP] Doubts concerning a general Insert method
2009/7/13 MEM tal...@gmail.com:
Hello, I'm trying to understand a general CRUD class that I've seen here:
http://www.phpro.org/classes/PDO-CRUD.html
I'm learning PHP and I have some doubts on this method to generally insert
data into DB. The class name is crud and here is the method:
public function dbInsert($table, $values) {
$this-conn();
$fieldnames = array_keys($values[0]);
$size = sizeof($fieldnames);
$i=1;
//construction of the prepared statment
$sql = INSERT INTO $table;
$fields = '( ' . implode(' ,', $fieldnames) . ' )';
$bound = '(:' . implode(', :', $fieldnames) . ' )';
$sql .= $fields.' VALUES '.$bound;
//prepares statement e saves it on variable $stmt
$stmt = $this-db-prepare($sql);
foreach($values as vals)
{
$stmt-execute($vals);
}
}
To place values on the DB we do:
$crud = new crud();
$values = array
(
array('animal_name'='bruce', 'animal_type'='dingo'),
array('animal_name'='bruce', 'animal_type'='kangaroo'),
);
$crud-dbInsert('animals', $values);
The doubts:
1) Names convention question:
Isn't more correct to call $columname, instead of $fieldname ?
The two terms are interchangeable in the context of a database.
2) Why do we have this?
$i=1
It's not used so I'd guess it's a remnant from an older version of the
method. Safe to remove it.
3) Here:
$fieldnames = array_keys($values[0]);
We are keeping on variable $fieldnames, the key value of the $values array,
when this array is on the position 0 ? And what is *actually* the value
returned, considering our array?
$values = array
(
array('animal_name'='bruce', 'animal_type'='dingo'),
array('animal_name'='bruce', 'animal_type'='kangaroo'),
);
You can use the var_dump function to dump the contents of $fieldnames
after that line has been executed and see for yourself.
In this case let's break it down...
$values[0] will give you the first element of $values, namely
array('animal_name'='bruce', 'animal_type'='dingo').
array_keys will return an array containing the keys from the
passed array, so in this case you'll get array('animal_name',
'animal_type').
4) Here:
foreach($values as $vals)
{
$stmt-execute($vals);
}
We are telling that, for each (line/element/index ???) of $values array, the
actual value will be given(?) to vals, and the pointer goes to the next
(line/element/index)... ?
We then execute the prepared statement, but I don't get what are we passing
as a param? I mean, what kind of think does the execute PDO method expects
as a param?
Why $stmt-execute($vals); and not only $stmt-execute(); ?
After it's finished building $sql use var_dump to look at it. You'll
see that the values are specified as :animal_name and :animal_type.
The : indicates to PDO that these are replaceable values.
The foreach will go through the $values array and for each row it will
pass the data (e.g. array('animal_name'='bruce',
'animal_type'='dingo') for the first time round the loop) to the
execute function which will effectively replace those elements in the
SQL statement and execute it.
For more info I suggest you Google for PDO prepared statements for
further reading.
-Stuart
--
http://stut.net/
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RE: [PHP] Doubts concerning a general Insert method
$values[0] will give you the first element of $values, namely
array('animal_name'='bruce', 'animal_type'='dingo').
array_keys will return an array containing the keys from the
passed array, so in this case you'll get array('animal_name',
'animal_type').
So... since $value is an associate array of arrays, we will get, on the first
key, not an array with 0, 1, like array(0,1); but
array('animal_name','animal_type'), yes?
When we use the implode over this array, we get:
animal_name, animal_type that is the string that will pass to be prepare using
the PDO prepare().
After it's finished building $sql use var_dump to look at it. You'll
see that the values are specified as :animal_name and :animal_type.
The : indicates to PDO that these are replaceable values.
Yes. And normally, to fill those replaceable values, I was used to use
bindParam();
I like this bindParam method because we can then use PDO::PARAM_INT and
PDO::PARAM_STR to more accurately control the data type flow...
The foreach will go through the $values array and for each row it will
pass the data (e.g. array('animal_name'='bruce',
'animal_type'='dingo') for the first time round the loop) to the
execute function which will effectively replace those elements in the
SQL statement and execute it.
Ok, so:
Our $sql will be: INSERT INTO $table (animal_name, animal_type) VALUES
(:animal_name, :animal_type)
We then prepare this $sql by doing:
prepare($sql); and the value of this preparation will be kept on a variable
name $stmt.
Finally, on the foreach, we will grab each value of the $values array, and keep
him, on a variable called $vals,
The $vals will contain this on the first occurrence of the loop:
array('animal_name'='bruce', 'animal_type'='ding')
and then, the var $vals will have this on the second occurrence of the loop:
array('animal_name'='bruce', 'animal_type'='kanguro')
etc.,
At the end of each of these loops, we will process the execute (that will send
the statement to the database).
$stmt-execute(array('animal_name'='bruce', 'animal_type'='kanguro').
So this execute will do A LOT, it will take away the 'array(' part, will see
the keys of these arrays (e.g. animal_name and animal_type) compare them with
the placeholder names given on the prepare statement and, replace the
placeholder names with the values inside on each of this array keys.
Is this correct?
Regards,
Márcio
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Re: [PHP] Doubts concerning a general Insert method
2009/7/13 MEM tal...@gmail.com:
$values[0] will give you the first element of $values, namely
array('animal_name'='bruce', 'animal_type'='dingo').
array_keys will return an array containing the keys from the
passed array, so in this case you'll get array('animal_name',
'animal_type').
So... since $value is an associate array of arrays, we will get, on the first
key, not an array with 0, 1, like array(0,1); but
array('animal_name','animal_type'), yes?
When we use the implode over this array, we get:
animal_name, animal_type that is the string that will pass to be prepare
using the PDO prepare().
Indeed.
After it's finished building $sql use var_dump to look at it. You'll
see that the values are specified as :animal_name and :animal_type.
The : indicates to PDO that these are replaceable values.
Yes. And normally, to fill those replaceable values, I was used to use
bindParam();
I like this bindParam method because we can then use PDO::PARAM_INT and
PDO::PARAM_STR to more accurately control the data type flow...
I'm not overly familiar with PDO, but I believe that's an alternative
way to do it. The execute method lets you do it in one method call.
The foreach will go through the $values array and for each row it will
pass the data (e.g. array('animal_name'='bruce',
'animal_type'='dingo') for the first time round the loop) to the
execute function which will effectively replace those elements in the
SQL statement and execute it.
Ok, so:
Our $sql will be: INSERT INTO $table (animal_name, animal_type) VALUES
(:animal_name, :animal_type)
We then prepare this $sql by doing:
prepare($sql); and the value of this preparation will be kept on a variable
name $stmt.
Finally, on the foreach, we will grab each value of the $values array, and
keep him, on a variable called $vals,
The $vals will contain this on the first occurrence of the loop:
array('animal_name'='bruce', 'animal_type'='ding')
and then, the var $vals will have this on the second occurrence of the loop:
array('animal_name'='bruce', 'animal_type'='kanguro')
etc.,
At the end of each of these loops, we will process the execute (that will
send the statement to the database).
$stmt-execute(array('animal_name'='bruce', 'animal_type'='kanguro').
So this execute will do A LOT, it will take away the 'array(' part, will see
the keys of these arrays (e.g. animal_name and animal_type) compare them with
the placeholder names given on the prepare statement and, replace the
placeholder names with the values inside on each of this array keys.
Is this correct?
Indeed.
-Stuart
--
http://stut.net/
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RE: [PHP] Doubts concerning a general Insert method
Nice. :-) Thanks a lot Stuart for your time and explanations.
Now that I have understand, I will try to move on, and understand how can we
introduce bindParams on it:
For a recall, here is the original class:
public function dbInsert($table, $values) {
$this-conn();
$fieldnames = array_keys($values[0]);
$size = sizeof($fieldnames);
$i=1;
//construction of the prepared statment
$sql = INSERT INTO $table;
$fields = '( ' . implode(' ,', $fieldnames) . ' )';
$bound = '(:' . implode(', :', $fieldnames) . ' )';
$sql .= $fields.' VALUES '.$bound;
//prepares statement e saves it on variable $stmt
$stmt = $this-db-prepare($sql);
foreach($values as vals)
{
$stmt-execute($vals);
}
}
However I do have some questions that maybe someone more experimented then me
could easily solve:
1)
The bindParams should look similar to this:
$stmt-bindParam(':animal_name', $animals-getName(), PDO::PARAM_STR );
$stmt-bindParam(':animal_type', $animals-getType(), PDO::PARAM_STR );
So, instead of looping trough an array of values, I will to do it for objects,
something like:
foreach($animals-listaAnimals() as $row) ...
Can I have some words on this so that I can properly try to add bindParam on
this class method.
2)
I also need to have a way to add PDO::PARAM_STR if the values is a string or
PDO::PARAM_INT if the values is int, PDO::PARAM_BOOL etc...
Is there a way to control this? Using something like is_integer() and
is_string(), inside if statement perhaps? If so, what about the Boolean?
Thanks a lot,
Márcio
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