Updating a MySql table from textbox values using php [closed] - php

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I have a welcome page which populates text boxes from a users table with the values of all fields for the id of the user who has logged in. What I would simply like to do, is write back those values to the table using an update statement based on the id of the user whose details are displayed if an 'update values' form button is clicked and return or stay on the same page. no data validation is required at this stage. if two of the fields in the dbase are named gas_sc and elec_sc how would I code this? The txt boxes were populated using $_SESSION["elec_sc"] = $elec_sc; when the user logged in.
Unfortunately I don't have much php knowledge and have been using cut and paste from other examples to get this far. I have looked at similar posts but couldn't see one to answer this question.

Answer 1

PDO
Refer this site for information about updating with PDO: https://phpdelusions.net/pdo_examples/update
It provides this example:
$sql = "UPDATE users SET name=?, surname=?, sex=? WHERE id=?";
$stmt= $pdo->prepare($sql);
$stmt->execute([$name, $surname, $sex, $id]);
Basically:
it creates a string called $sql
the field names are assigned to ?, which is a placeholder for the parameterized query
the $stmt is prepared
and then executed, by passing an array of the actual parameters [$name, $surname, $sex, $id]
This is already very similar to what you will need to do, but you will need to replace the field names with gas_sc and elec_sc, respectively and the parameter values with the values you have received.
You can also pass named parameters, see this example from the same source:
$data = [
'name' => $name,
'surname' => $surname,
'sex' => $sex,
'id' => $id,
];
$sql = "UPDATE users SET name=:name, surname=:surname, sex=:sex WHERE id=:id";
$stmt= $pdo->prepare($sql);
$stmt->execute($data);
Notice that here we have the syntax of :<paramname> inside the query and key-value pairs in the $data that we pass.
You need to use parameterized queries instead of hard-coding the values for security reasons (search for SQL injection for more information)
How to proceed
You can create an HTML form
<form action="/the/url/to/the/backend" method="POST">
<input type="hidden" name="id" value="<?php echo '123'; ?>"
<label for="gas_sc">
<input name="gas_sc" id="gas_sc" type="text">
</label><br>
<label for="elec_sc">
<input name="elec_sc" id="elec_sc" type="text">
</label><br>
<input type="submit" value="click on me!">
</form>
for action you will need to provide a valid URL that works
method could also be GET
labels are making the form appear more neatly
the for attribute of a label specifies what control it should be entangled with (by id)
the name attribute of an input specifies that the input's value will be sent to the server when the form is submitted
the submit input is the button which is responsible of submitting the form
How to collect values
If you have a whitelist of attributes, such as:
$attributes = ['gas_sc', 'elec_sc'];
then you can collect the values like this:
$data = ['id' => $_POST["id"]];
$params = ["id=:id"];
foreach ($attributes as $attribute) {
$params[]="{$attribute}=:{$attribute}";
$data[$attribute] = $_POST[$attribute] ?? null;
}
$sql = "UPDATE users SET " . implode(",", $params) . " WHERE id=:id";
$stmt=$pdo->prepare($sql);
$stmt->execute($data)
We initialize $data and $params, loop the $attributes and add each time a paramname=:paramvalue and a dataname => datavalue to them. Afterwards, we dynamically generate our query, by imploding $params into comma-separated value assignments and pass $data.
If you want to to it dynamically (but be careful about that), then you can build $attributes like this:
$attributes = array_keys($_POST);
Again, be careful, prevent any possible malicious inputs from doing harm. Yet, if no validation is needed, as you described, then you can do the above.

Answer 2

Its hard to view the problem without code, please paste your code and format it because its kinda hard to help you in the blindness.
For the other hand, tell us if you're using PDO or mysqli (for security, you should use PDO).
Anyways, what i readed, you should get the values from the text boxes using $_POST values, also using the names of the textboxes (in the html).
It should be something like this:
$firstTextbox = $_POST['name_textbox_html`];
$secondTextbox = $_POST['name_textbox2_html'];
Once you got those values, you should be able to make the html form take action to wathever you want, and use this variables in a SQL syntax using PDO or mysqli, by passing them as parameters to the function where you do the update, replacing the manual data you put normally in the update with the variables you use for saving the textbox values.
You can print the values of this variables that saves the textbox values by doing echo $firstTextbox and $secondTextbox