This would helps me a lot to understand how does loop works
Let say i've database table my_table (id,words) and here is example of database
INSERT INTO `my_table` VALUES (1,'hello manal');
INSERT INTO `my_table` VALUES (2,'nice manal');
INSERT INTO `my_table` VALUES (3,'pretty manal');
now imagine for 100,000 entries (huge) and i want to replce the word manal to jack and giving me results every line changed one by one
i'll use
$conn = mysql_connect('localhost','USER','PASS') or die(mysql_error());
mysql_select_db('my_table',$conn);
$sql = "SELECT * from my_table";
$result = mysql_query($sql,$conn);
while ($row = mysql_fetch_array($result)){
$old = $row['words'];
$id = $row['id'];
$new="jack";
$new = str_replace("manal", "$new", $old);
echo $new;
}
The loop
by that code it will works all at once which is impossible to my hosting server to apply all so i want to make it as loop ! i mean it will change the 1st database line then gives me the results echo $new; then change the 2nd database line then gives the results echo $new; and so on with no stop till last line.
so my important part is getting the results one by one ~thanks
The problem will be that your output is being buffered which is why you see all the results at the same time (at the end of the execution of the script).
You could add ob_flush(); flush(); within the loop before echo $new; an see if that helps. Regardless, the above example is going to execute pretty quickly so it isn't exactly going to be easily readable!
You better do this replace in the database itself and then you just print it out.
$sql = "UPDATE my_table SET words = REPLACE(words, 'manal', 'jack')";
Related
<?php
$connect = mysqli_connect("localhost", "root", "", "hempbag_db") or die("Connection failed");
$query= "Select * from tbl_sales";
$ress = mysqli_query($connect, $query);
$result = mysqli_fetch_array($ress);
foreach($result as $a)
{
echo $a['ID']; // This doesnt print although i used fetch array
}
foreach($ress as $a)
{
echo $a['ID']; // This works why???? This variable has only query run
}
?>
Why does the upper foreach does not run and lower one does? Can anyone explain please?
When you run a query, it returns a result:
$ress = mysqli_query($connect, $query);
var_dump($ress); // You will see it's a result.
At this point $ress just contains the result of what you just queried. Think of it like this:
You goto the warehouse, and you make and order for 1000 boxes of crackers. She heads to the back, and gets your boxes ready, and comes back and hands you a piece of paper with the order number. (This is $ress). Now, you can't loop through that, you can't do anything with that.
You now take that piece of paper, and you hand it to your assistant, and you say you want to get all the crackers on your trucks (This is now mysqli_fetch_array()). Your assistant goes, fetches it, and returns you the crackers.
Simply put, mysqli_query just returns an object like Result#1. From Result#1, mysql can tell you how many rows were returned mysql_num_rows(Result#1), or get actual data if it was a select query: mysqli_fetch_array(Result#1).
Now onto the reasoning: Performance. Let's say you didn't want 1000 crackers, you just wanted to know if they had 1000 crackers. If she came back with all the boxes of crackers and you had to count them yourself, it would be much more difficult. Instead, with that piece of paper, she can determine how many boxes you were able to order. Less data being transferred, and much more efficient.
Just a small note, in later versions of php, they made it so the result is iterable, meaning that if you try and loop through it, it will automagically call mysqli_fetch_array on that result, and return you the results.
Additionally, mysql_fetch_array will return one row from the database, and is not able to be looped through via foreach. Perhaps you were thinking of mysqli_fetch_all? This returns all rows and can be looped through (Although is a bit less performant than using a while loop with mysqli_fetch_array)
$ress = mysqli_query($connect, $query);
This line returns a result set which is Traversable. So your second foreach works fine.
whereas the following line (mysqli_fetch_array) gets one row at a time and makes it an array.
$result = mysqli_fetch_array($ress); // Suppose you have 3 rows, Now cursor is at row 1
echo $result["ID"]; // this will print FIRST row's ID
$result = mysqli_fetch_array($ress); // Now cursor is at row 2
echo $result["ID"]; // this will print SECOND row's ID.
$result = mysqli_fetch_array($ress); // Now cursor is at row 3
echo $result["ID"]; // this will print THIRD row's ID.
To echo all IDs
while($result = mysqli_fetch_array($ress)) {
echo $result["ID"];
}
I have a file file.php and inside my file I am using the code bellow to pull some data from my database and display some information.
My code is
$array = $_GET['theurl']; // My url looks like myfile.php?theurl=1,2,3 (id,s)
$sqlnt4 = "select * from mytable WHERE `id` IN ($array)";
$rsdt4 = mysql_query($sql);
$tc4a = mysql_fetch_assoc($rsdt4);
$mycomma4 = ",";
if ($tc4a['a_youtube'] == "#"){
}else{
while ($tc4 = mysql_fetch_assoc($rsdt4))
{
echo $tc4['a_youtube'];
echo ",";
}
}
I expect to echo the infos of the two id's (in array) inside my while function, but it returns the results only from the first.
Any ideas?
I am confusing on $sql :
$sqlnt4 = "select * from mytable WHERE `id` IN ($array)";
$rsdt4 = mysql_query($sql);
Can you take a look after changing below:
$sqlnt4 = "select * from mytable WHERE `id` IN ($array)";
$rsdt4 = mysql_query($sqlnt4);
First that's extremely vulnerable to security issues - I hope this isn't used in production and just for playing around.
I recommend switching to PDO, or at the very least securing your variables.
To put that array into the query, you need to implode it into a list, as such.
$list = implode(',', $array);
You can then use the list in the statement, which will look like 1,2,3.
Edit:
I've just realized your $array value isn't actually an array - have you missed code out or is it badly named?
mysql_fetch_assoc: "Returns an associative array that corresponds to the fetched row and moves the internal data pointer ahead." http://pt2.php.net/mysql_fetch_assoc
Try mysql_fetch_rows to return all matching rows into an array.
I have a problem. I have an array of values from database, when I try to pass it to a string with commas, it works fine on my localhost, but when I upload it to my online server, the string doesn't show any values. For example: select from table where in (,,) only shows the commas and in my xampp server it works excellent. Any ideas what this can be?
Here's the code:
<?php
$sql = "select id from users where gid = 1";
$result = mysql_query( $sql);
$cat_titles=array();
while( $row=mysql_fetch_assoc($result) )
{
$cat_titles[] = $row['id '];
// do stuff with other column
// data if we want
}
mysql_free_result( $result );
echo "<p>\n";
foreach($cat_titles as $v)
{
$cat_titles[]= $row['id'];
}
echo "</p>\n";
$cat_titles = implode(',',$cat_titles);
$cat_titles = substr($cat_titles,0,-2);
echo $cat_titles;
echo "select * from users where IN (".$cat_titles.")";
?>
A number of potential issues here:
You are not handling error conditions around you database access, so if you are having issue with your queries you would never know.
Your second select query doesn't specify a field in the WHERE clause, so it will never work
This section of code does absolutely nothing and is in fact where you problem likely lies.
foreach($cat_titles as $v)
{
$cat_titles[]= $row['id'];
}
Here $row['id'] won't have a value, so you are basically looping throguh your existing array and appending empty value to new indexes.
In all likelihood you could do this with a single query, it might help if you explain what you are actually trying to do.
You should not be using mysql_* functions. They are deprecated. Use mysqli or PDO instead.
i'm trying to make a long mysql query and process and update the row founded:
$query = 'SELECT tvshows.id_show, tvshows.actors FROM tvshows where tvshows.actors is not NULL';
$result = mysql_query($query);
$total = mysql_num_rows($result);
echo $total;
while ($db_row = mysql_fetch_assoc($result))
{
//process row
}
but after 60 second give me a timeout request, i have try to insert these in my php code:
set_time_limit(400);
but it's the same, how i can do?
EDIT:
only the query:
$query = 'SELECT tvshows.id_show, tvshows.actors FROM tvshows where tvshows.actors is not NULL';
takes 2-3 second to perform, so i think the problem is when in php i iterate all the result to insert to row or update it, so i think the problem is in the php, how i can change the timeout?
EDIT:
here is the complete code, i don't think is a problem here in the code...
$query = 'SELECT tvshows.id_show, tvshows.actors FROM tvshows where tvshows.actors is not NULL';
$result = mysql_query($query);
$total = mysql_num_rows($result);
echo $total;
while ($db_row = mysql_fetch_assoc($result)) {
//print $db_row['id_show']."-".$db_row['actors']."<BR>";
$explode = explode("|", $db_row['actors']);
foreach ($explode as $value) {
if ($value != "") {
$checkactor = mysql_query(sprintf("SELECT id_actor,name FROM actors WHERE name = '%s'",mysql_real_escape_string($value))) or die(mysql_error());
if (mysql_num_rows($checkactor) != 0) {
$actorrow = mysql_fetch_row($checkactor);
$checkrole = mysql_query(sprintf("SELECT id_show,id_actor FROM actor_role WHERE id_show = %d AND id_actor = %d",$db_row['id_show'],$actorrow[0])) or die(mysql_error());
if (mysql_num_rows($checkrole) == 0) {
$insertactorrole = mysql_query(sprintf("INSERT INTO actor_role (id_show, id_actor) VALUES (%d, %d)",$db_row['id_show'],$actorrow[0])) or die(mysql_error());
}
} else {
$insertactor = mysql_query(sprintf("INSERT INTO actors (name) VALUES ('%s')",mysql_real_escape_string($value))) or die(mysql_error());
$insertactorrole = mysql_query(sprintf("INSERT INTO actor_role (id_show, id_actor, role) VALUES (%d, %d,'')",$db_row['id_show'],mysql_insert_id())) or die(mysql_error());
}
}
}
}
Should definitely try what #rid suggested, and to execute the query on the server and see the results/duration to debug - if the query is not a simple one, construct it as you would in your PHP script, and only echo the SQL command, don't have to execute it, and just copy that in to the server MySQL command line or whichever tool you use.
If you have shell access, use the top command after running the above script again, and see if the MySQL demon server is spiking in resources to see if it really is the cause.
Can you also try a simpler query in place of the longer one? Like just a simple SELECT count(*) FROM tvshows and see if that also takes a long time to return a value?
Hope these suggestions help.
There are so many problems with your code.
Don't store multiple values in a single column. Your actors column is pipe-delimited text. This is a big no-no.
Use JOINs instead of additional queries. You can (or could, if the above weren't true) get all of this data in a single query.
All of your code can be done in a single query on the server. As I see it, it takes no input from the user and produces no output. It just updates a table. Why do this in PHP? Learn about INSERT...SELECT....
Here are some resources to get you started (from Googling, but hopefully they'll be good enough):
http://www.sitepoint.com/understanding-sql-joins-mysql-database/
http://dev.mysql.com/doc/refman/5.1/en/join.html
http://dev.mysql.com/doc/refman/5.1/en/insert-select.html
What is Normalisation (or Normalization)?
Let me know if you have any further questions.
I am currently still learning PHP so some things I still struggle with.
I have been taking it slowly and reading tutorials which has helped but I can't figure this one out.
I have a database table (in mysql) with let's say, 100 urls. There is a column called 'url' and a second column 'text'. I already have the pagination code which works, so will also be using that.
What I want to do is echo out the URLs (which are all in folder called blog in the root of my site), but use the text as the link.
So for example the first three rows in my table might be:
url
001.php
002.php
003.php
text
random text
some random text
more text
when echoed out the links show the text from the column text like:
random text
some random text
more text
and will open to the relevant url when clicked
I'm guessing it will need some kind of loop to collect all the URLs and save me adding the link text in manually, and then my pagination code will split them up.
This is my first time asking a question on here, so if it wasn't clear enough or you need more info, let me know.
I have done multiple searches on the internet but can't seem to find a tutorial.
Assuming you connect to a local mysql server with username "root" and password "root", and have your url's stored in a table named url_table in a database named url_database you could do something like:
$connection = mysql_connect("127.0.0.1","root","root"); // Connect to the mysql server
mysql_select_db("url_database"); // Open the desired database
$query = "SELECT url,text FROM url_table"; // Query to select the fields in each row
$result = mysql_query($query); // Run the query and store the result in $result
while($row = mysql_fetch_assoc($result)) // While there are still rows, create an array of each
{
echo "<a href='".$row['url']."'>".$row['text']."</a>"; // Write an anchor with the url as href, and text as value/content
}
mysql_close($connection); // close the previously opened connection to the database
What you need is to:
get your result array from the database. Use something like
$query = "SELECT * FROM urls";
$result = mysql_query($query);
For every row in your results table, show the corresponding url. Note that calling mysql_fetch_array on a result resource, returns the first row of the results table when called for the first time, the second on second time etc. The function returns false when there are no more rows to return.
(See more on that in the mysql_fetch_array() documentation)
While( $row = mysql_fetch_array($result) ){
echo '<a href='.$row['url'].'>'.$row['text'].'</a>';
}
Here is a sample you can start with:
$con = mysql_connect("host","user","password");
if (!$con) {
die('Could not connect: ' . mysql_error());
}
mysql_select_db("my_db", $con);
$result = mysql_query("SELECT the_url, the_text FROM my_table");
while($row = mysql_fetch_array($result))
{
echo '"' . $row['the_text'] . ' <br />';
}
mysql_close($con);
First, you want to select only the relevant lines in your database for the page that the user is currently viewing. For example, if the user is viewing page 2, with entries 15-30 present, we only want to pull those entries from the database. This is an efficiency concern.
The code you're after is something like this:
$link = mysql_connect(/*connection parameters go here*/);
if ($link === false)
die;
mysql_select_db('my_database');
$result = mysql_query("SELECT text, url FROM my_table LIMIT 15,30");
print "<ul>\n";
while ($row = mysql_fetch_assoc($result)) {
print "<li>{$row['text']}</li>\n";
}
print "</ul>\n";
mysql_close();
The first three lines establish a connection to the database, and exit the script if an error occurs.
The next line selects the appropriate database on the server.
The next block runs the appropriate query for the second page. After the query is run, a 'result' is stored in $result. This result is comprised of a number of rows, and mysql_fetch_assoc($result) obtains those lines one at a time. It then formats these lines into the appropriate link format and outputs them. The entire set of links is wrapped in a dot-point list.
Finally, mysql_close() closes the connection to the database.
I'm assuming since you just started you're probably doing all this procedurally.
First you want to query the database and get the info you need.
<?php
$result = mysqli_query($link, "SELECT url, text FROM table_name");
while ($row = mysqli_fetch_array($result)) $hrefs[] = $row;
foreach ($hrefs as $href) {
echo "".$href['text']."";
}
?>
Please note I've done no error handling here.