I have a update.php page which checks checkbox values and updates the data in the DB.
For example, the sport_table looks like this (primary key is a combination of MemberID-Sport):
MemberID | Sport
John | Football
John | Rugby
John | Cricket
Paul | Football
Paul | Rugby
Mike | Cricket
So what I want to do is get get the value from the checkboxes on my webform and update them as necesary in the db table.
I have tried the following code:
$sport = $_POST["sport"];
for ($i=0; $i < sizeof($sport); $i++) {
$sql = "UPDATE sport_table
SET sport='$sport[$i]', MemberID='$username'";
$result = mysqli_query($conn, $sql);
But receive an errors duplicate keys when checking/unchecking boxes and then clicking update.
Making a few assumptions, this is where you might need to be looking:
First, if using checkboxes, you need to allow for multiple answers in the submission with HTML that looks something like this:
<input type="checkbox" name="sport[]" value="Football">Football</input>
Note the [] in the field name. This ensures PHP will parse the field as an array which can have multiple values.
Second, PHP needs to process the array if it exists and always validate user input. Learn about SQL Injection, Never take content direct from the request and use in an SQL query. It will save you a heap of bother one day.
$validSports=array('Football','Rugby','Cricket','Football');
// $_POST['sport'] will not be set if no boxes are checked
if(isset($_POST['sport']) &&
is_array($_POST['sport'])) {
// Remove previous entries from the table for this member.
$sql = "DELETE FROM sport_table WHERE MemberID='$username'";
$result = mysqli_query($conn, $sql);
foreach($_POST['sport'] as $sport) {
// See how we validate the user input here, there are other ways
if(in_array($sport, $validSports)) {
$sql = "INSERT INTO sport_table
SET sport='$sport[$i]', MemberID='$username'";
$result = mysqli_query($conn, $sql);
}
}
}
Thirdly, I've missed out the example code to keep it simple, but in practice, always check the $result value from mysqli_query and if $result === false then you need to handle the error - probably by writing to a log somewhere.
Finally, check the indexes on your sport_table to make it fast. An index on MemberID would be sufficient for the use cases above although a unique index on (MemberId,sport) may be more appropriate to mitigate against data duplication.
Part of a script I am writing requires me to know exactly how a result set gets it's information from a MYSQL query.
I have a standard result from an SQL query, which I then make a row array using fetch_array.
Whilst looping through this content let's say I delete one of the rows I find from the table. If I reset the pointer of the result back to the first, will I find that row again even though it no longer exists, find an empty row, or miss that row entirely?
In other words is the result asking MYSQL for each row as it needs it, or does it get the whole array in one go so it will not pickup on any changes to the table afterwards?
Cheers in advance
EDIT
$result = $conn->query("SELECT ID, value FROM table");
while($row=$result->fetch_array()){
if(x){
$conn->query("DELETE FROM table WHERE ID=$row['ID']");
mysqli_data_seek($result,0);
}
}
The question is will that deleted row be repeated after the reset, get skipped or return something else such as NULL?
No, it will not delete that row inside initial fetched result set.
But of course it will delete the row in your present table.
If you try to reset the pointer, the initial result set with that row still resides. Not unless you overwrite it with another one.
Consider this example. Lets say you have this inside your table:
+----+--------+
| id | value |
+----+--------+
| 1 | test1 |
| 2 | test2 |
| 5 | test5 |
+----+--------+
If you make this kind of operation:
$result = $conn->query('SELECT id, value FROM mytable'); // sample query
while($row = $result->fetch_assoc()) { // fetch all results
if($row['id'] == 5) { // some condition
$conn->query('DELETE FROM mytable WHERE id = 5'); // delete one row in table
}
}
$result->data_seek(0); // reset the pointer
while($row = $result->fetch_assoc()) { // fetch the same result set
echo $row['id'] . '<br/>';
}
It will delete that particular row in your table but not the one in the initial result.
At initial load, it will show:
1
2
5
If you refresh it, now 5 will be gone since its a new request and another result set called.
I have three tables (I simplified it in this question) :
Table 1
id | Name
-----------
1 | John
2 | Smith
Table 2
id | Title
-----------
1 | Developer
2 | Web Developer
3 | A New Title
Table 3 (links between 1 and 2)
idName | idTitle
-----------
1 | 1
1 | 2
2 | 1
My problem is with the update page. My HTML is <select multiple> ... options ... </select> and I am using chosen to select and deselect options. I am trying to do this with PHP only.
Lets say that we have the following scenario:
The administrator wanted to remove the 'Developer' Title for 'John' and add 'New Title' for 'John'.
He/She will deselect Title id 1 and select id 3. When He/She submits the form I will get two select values: id 1 (the one that he selected) and id 2 (the one that was already there). But I will not get id 3 because he deselected it.
What I am struggling with is : when the user posted the new selected values the ones that were deselected were not submitted with the form. There is no way for me to track the ones that were deselected so I can delete them from my table. How do you update your table with the new changes then? Do you delete what is already existed in that table and add the ids again? Is there a better option?
UPDATE :
It seems #wander answer is less destructive than the other ones. However, #wonder did not explain how to compute step 4 in his answer. to distinguesh between new selected options, already existing selected options, and deselected options.
There's no need to submit the deselected one. e.g.
John has two titles(Developer and Web Developer) saved in database.
The administrator opens the page, selects 'New Title', deselects 'Developer' and clicks submit.
Now on server side, we can get
the title list of John stored in database: Developer and Web Developer
title list submitted from the users: Web Developer and New Title
We compare the two title lists and figure out: we shall delete Developer title and add New Title on John.
You could add hidden fields before the select menu which will cause 0/falsey values to also be sent to PHP.
<input type="hidden" name="stuff[]" value="0" />
<input type="hidden" name="stuff[]" value="0" />
<input type="hidden" name="stuff[]" value="0" />
<select multiple name="stuff[]">
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
</select>
This is similar to how you would send unchecked check boxes to the server:
https://stackoverflow.com/a/1992745/268074 (note the answer without JS)
You can dump your old values in a hidden select, so you'll get them when handling your form.
<!-- Invisible select field -->
<select multiple name="oldData[]" style="display:none;" aria-hidden="true">
<option value="1">1</option>
<option value="2" selected>2</option>
<option value="3" selected>3</option>
</select>
<!-- Real select field -->
<select multiple name="data[]">
<option value="1">1</option>
<option value="2">2</option>
<option value="3">3</option>
</select>
Note: I was inspired by #Petah's answer, don't forget to upvote him :-).
Let's say we have $old_titles list with titles from db, and $new_titles titles from submit.
$add = array_diff($new_titles, $old_titles);
$delete = array_diff($old_titles, $new_titles);
$add - list of titles to add, $delete - list of titles to delete.
Add action:
$dbh->prepare('INSERT INTO table3(idName, idTitle) VALUES (:idName, :idTitle)');
foreach($add as $titleId) {
$dbh->execute(['idName' => $userId, 'idTitle' => $titleId]);
}
Delete action:
$dbh->prepare('DELETE FROM table3 WHERE idName = :idName AND idTitle = :idTitle');
foreach($delete as $titleId) {
$dbh->execute(['idName' => $userId, 'idTitle' => $titleId]);
}
Not sure why everybody keeps using hidden input fields to track the existing data. When you POST your form, you can just retrieve the original values from the database. That's a lot safer then depending on user input, because even hidden fields can be altered. I know it won't matter too much in this particular situation, but I think it's best to always use the best practise.
Now in PHP you have two options. The first would be to delete all relations and then add the new relations. The second would be to delete all that wasn't posted and add/update the relations that where.
Although the second options might seem to be the "least destructive" as you call it, it is the easiest and least error prone way. The only reason I would abandon this tactic is when I would store extra data in the relations table. EG: date added (when did somebody get into a function) or added by user.
How would you go about it (method 2)?
Keep in mind that I use a method that tries to continue whenever possible. Another approach would be to halt when false data is posted.
<?php
if (array_key_exists("relations",$_POST) && is_array($_POST["relations"])) {
//no duplicates, you dont want to store the same function twice
//only integers
$list = array_unique(array_filter($_POST["relations"], "is_int"));
$csv = implode(',', $list);
//get the userid hoewever you normally would
$userId = 1
//Delete existing
$query = "DELETE FROM Table3 WHERE idname=".$userId
//insert all posted functions
//I select the id's from the actual table so it will never inserted a none existing ID.
//this approach never has duplicates, so the duplicate check in the beginning is redundant now, but I leave it incase I change this.
$query = "INSERT INTO Table3 (idName, idTitle) SELECT ".$userId.", Id FROM Table2 WHERE id IN (".$csv.")".
//execute queries
} else {
//nothing posted, delete all relations
}
?>
Now if you only want to insert new data and remove none-existing
<?php
if (array_key_exists("relations",$_POST) && is_array($_POST["relations"])) {
//no duplicates, you dont want to store the same function twice
//only integers
$list = array_unique(array_filter($_POST["relations"], "is_int"));
$csv = implode(',', $list);
//get the userid hoewever you normally would
$userId = 1
//Delete existing
$query = "DELETE FROM Table3 WHERE idname=".$userId." AND idTitle NOT IN (".$csv.")"
//only insert new functions
//I select the id's from the actual table so it will never inserted a none existing ID.
//this approach never has duplicates, so the duplicate check in the beginning is redundant now, but I leave it incase I change this.
$query = "INSERT INTO Table3 (idName, idTitle) SELECT ".$userId.", Id FROM Table2 WHERE id IN (".$csv.") AND id NOT IN (SELECT idTitle FROM table3 WHERE idName=".$userId.")".
//execute queries
} else {
//nothing posted, delete all relations
}
?>
The only better way is the simplest one, remember KIS
on update you just need to do following
DELETE FROM table3 WHERE idName=??
and then insert all selected idTitles again in table3
This can be done in two SQL statement without knowing which value has been de-selected. Following these 2 steps
1) In your PHP, create a comma separated list of all selected option. For example: 2, 3.
2) Then execute the following statements:
DELETE FROM tblLink WHERE idName = $id AND idTitle NOT IN ($list);
INSERT IGNORE tblLink (idName, idTitle)
SELECT $id, id FROM tblTitle WHERE id IN ($list);
Note: for shake of simplification, I use $id and $list in my example. When you intent to use it, you should properly prepare and bind parameter properly. Make sure that idName and idTitle are primary key to make it work.
To my opinion you have to check what actions should be performed first. This is a small example that you can run here http://sandbox.onlinephpfunctions.com/code/0fa11b3c9f846e344c912f5a3e994eea5e9cac34.
First run a select on Table 3 for idName=1 the output would be an array of idTitle's (1,2). In the following example the $array1 is the output of such a select statement and $array2 is the array of new idTitle's for the same idName that will have to be updated or deleted or inserted. If for example the new idTitles for a user are more or less than the previous ones then there you should have some sort of control over it in order to decide what queries you will run to the database.
$array1 = array(1,7,3,5);// initial idTitles try it on the above link (php sandbox) with more or less values
$array2 = array(1,4,3,6);//new idTitles try it on the above link (php sandbox) with more or less values
$count1=count($array1);
$count2=count($array2);
$diff=$count1-$count2;
if ($diff==0) {
$result1=array_values(array_diff_assoc($array2,$array1));
$result2=array_values(array_diff_assoc($array1,$array2));
$countr=count($result1);// or $result2 it is the same since they have the same length
$cr=0;
while($cr < $countr) {
print_r("update tblname set val=$result1[$cr] where id=theid and val=$result2[$cr]\n");
$cr++;
}
}
if ($diff!=0) {
$result1=array_diff($array2,$array1);
$result2=array_diff($array1,$array2);
if(count($result2)>0) {
foreach($result2 as $r2) {
print_r("delete from tblname where id=theid and val=$r2\n");
}
}
foreach($result1 as $r1) {
print_r("insert into tblname where id=theid and val=$r1\n");
}
}
How I would do it would extend the 1st table
id | Name | Title IDs
1 | John | 1,2
2 | Smith | 1,3
Each time the row is updated I would simply just replace the title_ids fields and be done with it.
After registering at my site, I want the user to select some elements from a table that already exists in my DB, and add them to "their" column in another table.
Say this is the existing table in a MySQL DB:
ID Item Color
1 Car Red
2 Apple Green
3 Trophy Gold
4 Suit Black
I would want the user to fill out a form where they:
Are presented with a dropdown list, to choose items from (based on the existing table).
When they have chosen up to x amount of items, they submit their "inventory" which..
Adds the selected items to their own column in a table that holds "user_inventory"
So this second table (user_inventory) should look something like this:
User_id item_id1 item_id2 item_id3
1 4 3 1
2 3 1 4
3 2 4 1
4 2 4 3
I don't expect you to write the code for me or anything, but I would be thrilled if you could answer these questions:
Is this possible?
Can you direct me to a similar type of thread or article that helps me write the code?
If you can not direct me anywhere, please help me in whichever way you see fit.
It is possible.
Firstly, read from the "existing" db table to create the select menu, example:
<select name="item">
<?php
$sql = "SELECT * FROM existing";
$query = mysqli_query($mysqli, $sql);
while ($result = mysqli_fetch_array($query)) {
$item = $result['item'];
echo "<option value='$item'>$item</option>";
}
?>
</select>
This will create the "Item" select menu, I'm sure you can figure out how to do the other menus by yourself, all that is left now is to submit and store into the new table which I assume you already know how to do.
if(isset($_POST['yoursubmitname'])) {
$item = $_POST['item'];
/// RUN THE INSERT COMMAND HERE //
}
i have 1 table named tbl_sales. the ff data in tbl_sales are
id | total |
1 | 100 |
my question is this. i want to update "total" by multiplying it to whatever values in textbox.
this is my code so far to display textbox. i echo it so that everytime i add order it will appear on every table row
echo '<td>'.$vats_tot.'</td>'; //- the value display in this row is from database.
echo 'input type = "text" name = "ds"/>;
my problem is this. i want to multiply this the value from this textbox to "$vats_tot" which is from database value. can it be possible to multiply this?
Try like
$txt_val = $_POST['ds'];
$sql = "UPDATE tbl_sales SET total = total * $txt_val";
sql query for your problem
$textbox_value=$_post['textbox_id'];//To get TextBox Value
update **[table_name]** set total=(total*$textbox_value) where id=1;//To update the data into the table