I have 2 tables in the database, the table circle and the table gossips.
The table circle has 3 columns: id, idfrom, idto.
The table gossips has id, userid, gossip.
My objectif is to echo all the gossips only if the userid of this gossip (idto) and the id of the pageuser(idfrom) are on the same row in the table circle.
I wrote this code,
$query = 'SELECT * FROM gossips ORDER BY id DESC';
$result = mysqli_query($cxn, $query)
or die("Couldn't execute query");
$querycircle = 'SELECT idfrom,idto FROM circle WHERE idfrom="{$pageuserid}" ';
$resultcircle = mysqli_query($cxn, $querycircle)
or die("Couldn't check if user in circle.");
while($row = mysqli_fetch_assoc($result))
{
while($rowcheck = mysqli_fetch_assoc($resultcircle))
{
if($row['userid'] == $rowcheck['idto'] || $row['userid'] == $_COOKIE['id']){
echo '<div class="gossip">'.$row['gossip'].'</div>';
}
}
}
But it doesn't seem to work properly.
Do you intend to get the same data with mysqli_fetch_assoc($resultcircle)) on each round of the first while-loop?
Then you should buffer this data in an array first, as executing mysqli_fetch_assoc will always give you the next data set on each successive call. It will not restart on top of the data.
(Btw, this is better: while(null !== ($rowcheck = mysqli_fetch_assoc($result))))
Another method to realize your objective is to do only one combined SQL request.
EDIT: Sudip Pal is fast, look at his answer for a combined request! ;)
Try the single SQL query for this and then try with one while loop.
Select A.gossip from gossips A, circle B where A.userid=B.idto and B.idfrom="{$pageuserid}" order by A.id DESC;
NOTE: you can also compare the COOKIE value by adding the extra comparison on the query, like and B.userid=$_COOKIE["id"] (better to save the cookie value in a variable)
Related
This is my table:
All I want to do is to obtain the '75' int value from the 'expquim' column to later addition that number into another (75+25) and do an UPDATE to that camp (now it is 100).
Foremost, there are dozens of ways to accomplish what you want to do. If you're querying the table, iterating over results and doing some conditional checks, the following will work for you. This is pseudo code... Check out the function names and what parameters they require. $db is your mysqli connection string. Obviously replace tablename with the name of your table. The query is designed to only select values that are equal to 75. Modify the query to obtain whatever results you want to update.
This should get you close to where you want to be.
$query = "SELECT * FROM tablename WHERE idus='1'";
$result = mysqli_query($db, $query);
while($row = mysqli_fetch_assoc($result)) {
if($row['expquim'] == 75){
$query2 = "UPDATE tablename SET expquim='".$row['expquim']+25."' WHERE idus='".$row['idus']."' LIMIT 1 ";
$result2 = mysqli_query($db,$query2);
}
}
How do I echo the latest values in column1? The below code echos the values before the update.
while($line = mysql_fetch_array($result)) {
$Student = $line["calss8"];
$querySf = "SELECT SUM(ABC) AS val1 FROM tbl1 WHERE student = '$Student'";
$resultSf = mysql_query($querySf);
$rSf = mysql_fetch_array($resultSf);
$totalSf = $rSf['val1'];
$totTMonth = $totalSf;
mysql_query("UPDATE tbl4 SET column1 = $totTMonth WHERE student = '$Student' LIMIT 1");
}
echo $line["column1"].",,";
As far as I know, you'll have to make a separate query to see what was just updated. I mean, run your select, perform your update, then do another select. You can get general information like how many rows were updated, but I don't think you can get specific information like the changed values in a column. Phil was right in suggesting that you should just print out the '$totTMonth' value since that is what you are updating your column with. That would be less overhead than doing another query to the database.
I think that problem starts before the code above. This code line will display the select results :echo $line["column1"].",,";. The variable $line is set before the code above. My solution is to do the following:
$result1 = mysql_query("SELECT column1 FROM student ..."); /* I insert the select query here */
While($row= mysql_fetch_array($result)) {
echo $row['column1'].",,";
}
What is the right way of checking if the required data is in the database?
What I use currently is,
mysql_query("SELECT anyfield FROM table WHERE field='$data'");
and then check the if any rows are affected.
But I dont really have any use with the extracted data anyfield.
Eventhough the resource usage is so minor here, what is the right way to check if data exists in a db without extracting any other fields from the table?
Let the database count and retrieve the count data from the query.
$result = mysql_query('SELECT COUNT(*) FROM `table` WHERE `field` = ...');
if (!$result) {
die(mysql_error());
}
if (mysql_result($result, 0, 0) > 0) {
// some data matched
} else {
// no data matched
}
$result = mysql_query("SELECT `field` FROM `table` WHERE `field` = '".$data."'");
if (mysql_num_rows($result)){
// Rows exist
}
OR
$result = mysql_query("SELECT COUNT(`field`) as count FROM `table` WHERE `field` = '".$data."'");
$row = mysql_fetch_array($result);
if ($row ['count']){
// Rows exist
}
I would ensure, if I was checking for data, that as little data was returned as possible.
Fetch one field (I usually do id) and ensure you use LIMIT, eg. LIMIT 1... assuming you only want to know if any record exists.
Because you're using a PHP variable to find a record, if it suits your situation, you could perhaps do a LEFT JOIN on the first SQL line that gets $data, but that might just as easily be overkill for what you need.
I have this
$sql = "SELECT id FROM table";
$result = mysql_query($sql) or die(mysql_error());
while($row = mysql_fetch_array($result)){
echo $row['id'];
}
This echo's all id's found in the table.
How can I choose to echo only a selected id.
Say the second id found on the table?
EDIT
I think I have confused people and myself aswell.
Let me try to explain again.
Using the above query I can echo all results found in the table with echo $row['id'];
However I do not want echo all results, just selected ones.
You guys have suggested I use limit or a Where clause.
If I do this I will be limited to just one record. This is not what I want.
I want to echo a selection of records.
Something likes this
echo $row['id'][5], $row['id'][6], $row['id'][6]
But obviously this is incorrect syntax and will not work but hopefully you get what I am trying to do.
Thanks
If you only want the second row then you could change your query to use offset and limit e.g.
SELECT id FROM table LIMIT 1, 1
You could also use a for loop instead of the while loop and then put in a conditional.
UPDATE
Just noticed comments above - you also need to sort the PHP bug by changing mysql_fetch_array to mysql_fetch_assoc.
UPDATE 2
Ok based on your update above you are looking to get all of the rows into an array which you can then iterate over.
You can just use mysql_fetch_array and then use $array[0]. For example:
$sql = "SELECT id FROM table";
$result = mysql_query($sql) or die(mysql_error());
$ids = array();
while($row = mysql_fetch_array($result)) {
$ids[] = $row[0];
}
From what I can gather from your questions you should not be selecting all records in the table if you wish to just use the Nth value, use:
SELECT id FROM table LIMIT N, 1
That will select the Nth value that was returned. Note: The first result is 0 so if you wish to get the second value the Nth value should be 1.
mysql_data_seek() let's you jump to a specific data-set(e.g. the 2.nd)
Example:
$sql = "SELECT id FROM table";
$result = mysql_query($sql) or die(mysql_error());
//get the 2nd id(counting starts at 0)
if(mysql_data_seek($result,1))
{
$row=mysql_fetch_assoc($result);
echo $row['id'];
}
OR:
use mysqli_result::fetch_all
It returns an array instead of a resultset, so you can handle it like an array and select single items directly (requires PHP5.3)
I want to fetch the last result in MySQL database table using PHP. How would I go about doing this?
I have 2 Columns in the Table, MessageID(auto) & Message.
I already know how to connect to the database.
Use mysql_query:
<?php
$result = mysql_query('SELECT t.messageid, t.message
FROM TABLE t
ORDER BY t.messageid DESC
LIMIT 1') or die('Invalid query: ' . mysql_error());
//print values to screen
while ($row = mysql_fetch_assoc($result)) {
echo $row['messageid'];
echo $row['message'];
}
// Free the resources associated with the result set
// This is done automatically at the end of the script
mysql_free_result($result);
?>
The SQL query:
SELECT t.messageid, t.message
FROM TABLE t
ORDER BY t.messageid DESC
LIMIT 1
...uses the ORDER BY to set the values so the highest value is the first row in the resultset. The LIMIT says that of all those rows, only the first is actually returned in the resultset. Because messageid is auto-increment, the highest value is the most recent one...
Records in a relational database do not have an intrinsic "order" so you cannot fetch the "last" record without some kind of ORDER BY clause.
Therefore, in order to fetch the "last" record, simply reverse the ORDER BY clause (change ASC to DESC or vice versa) then select the first result.
If you have an auto-increment field and you just want to find the last value that was inserted, you can use the fact that the auto-increment fields are ever-increasing (therefore the "last" one will be the one with the highest value) and do something like this:
SELECT *
FROM my_table
ORDER BY id_field DESC
LIMIT 1
Of course you can select the last row by sorting DESC in your query. But what if you want to select the first row and then the last. You can run a new query, but you can also use the function mysql_data_seek. check code below:
$result = mysql_query('YOUR QUERY') or die('Invalid query: ' . mysql_error());
$row_first = mysql_fetch_array($result);
mysql_data_seek($result , (mysql_num_rows($result)-1));
$row_last = mysql_fetch_array($result);
Hope this helps
The MySql query would look like this:
select MessageID, Message
from Table
order by MessageID desc
limit 1;
I am too rusty with PHP to give you the right syntax for executing this.
This query works because you have an auto-incrementing identifying field (MessageID). By ordering the results by that field in descending (largest to smallest) order we are effectively returning the records in the table in reverse order. The limit 1 clause simply limits the result set to one record - the last one in the table.
What do you mean by "the last result"? You need to precise a bit more.
Do you mean "the last entry I registered"?
In this case you should use the appropriate method (depending on the extension you are using) mysqli->insert_id OR mysql_insert_id.
If you mean "the latest entry in the table", an SQL query such as Andrew Hare's is just what you need.
Do you mean the last record or do you need the id of the most recently inserted record? For that you would use the PHP mysql_insert_id() function. Or if you are using the myusqli extension use $mysqli->insert_id.
for some reason (which I don't know why), my boss force me to get the data in this way:
$message_arr = array();
while ($row = mysql_fetch_assoc($result)) {
$message_arr['messageid']= $row['messageid'];
$message_arr['message']= $row['message'];
}
return $message_arr;
Of course, you need everything from OMG Ponies's answer I'm just telling you another way to do it =)
I hope this help.
You should use SELECT query. How SELECT works.
SELECT * FROM table - selects everything in a table (id, row 1, row 2,...)
SELECT id FROM table - selects only particular row from table.
If you now know, how to select, you can use additional logic.
SELECT * FROM table ORDER by id DESC LIMIT 1;
selects everything from table table, orders it by id - orders it DESCENDING and limits the query to only one result.
If you would do it like this:
SELECT * FROM table ORDER by id ASC limit 1; - you would get 1 entry into database.
You can order it by any row you want.
Hope it helps.
One thing to remember is that data does not get saved in the insertion order in any MYSQL database. So in order to get the last entered record u will have to have an auto increment field. Since there is an auto increment field in this table we are good to go.
The below script will help to get the last entered record
<?php
$sql = "SELECT * FROM table_name ORDER BY MessageID DESC LIMIT 2";
$result_set = mysql_query($sql);
if($result_set){
while($row = mysql_fetch_array($result_set)) {
echo "Message Id: ".$row['MessageID']."<br>";
echo "Message: ".$row['Message']."<br>";
}
//creating alert
echo "<script type=\"text/javascript\">alert('Data was Retrieved
successfully');</script>";
}
else{
//creating alert
echo "<script type=\"text/javascript\">alert('ERROR! Could Not Retrieve
Data');</script>";
}
?>
The query selects all the records in the table and orders them according to the descending order of the MessageID (as it is the auto increment field) and limits the returned result to only one record. So since the table is ordered according to the descending order of the MessageID only the last entered record will be returned.
NOTE: if you are using a newer version you will have to use mysqli_query($connection_variable,$sql); instead of mysql_query($sql); and mysqli_fetch_array($result_set) instead of mysql_fetch_array($result_set)
$result = mysql_query('select max(id) from your_table ') or die('Invalid query: ' . mysql_error());
while ($row = mysql_fetch_assoc($result)) {
echo $row['id'];
echo $row['message'];
}
//
//
mysql_free_result($result);
simple like that
this code of php works fine
SELECT t.messageid, t.message
FROM TABLE t
ORDER BY t.messageid DESC
LIMIT 1
if you don't have concurrent entries going into some table.b'cause concurrent entries may not go in accordance of their insertion order.
$statement = $PDO->prepare("
SELECT MessageID,
Message
FROM myTable
ORDER BY MessageID DESC
LIMIT 1;
");
$statement->execute();
$result = $statement->fetch(\PDO::FETCH_ASSOC);
echo $result['MessageID']." and ".$result['Message'];