I know this is very simple, but I haven't used PHP/MySQL in a while and I have been reading other threads/php website and can't seem to get it.
How can I query a single row from a MySQL Table and print out all of the fields that have data in them? I need to exclude the NULL fields, and only add those that have data to an html list.
To clarify, I would like to display the field data without specifying the field names, just for the reason that I have a lot of fields and will not know which ones will be NULL or not.
What you've outlined requires 4 basic steps:
Connect to the database.
Query for a specific row.
Remove the null values from the result.
Create the html.
Step 1 is quite environment specific, so that we can safely skip here.
Step 2 - SQL
SELECT * from <tablename> WHERE <condition isolating single row>
Step 3 - PHP (assuming that $query represents the executed db query)
//convert the result to an array
$result_array = mysql_fetch_array($query);
//remove null values from the result array
$result_array = array_filter($result_array, 'strlen');
Step 4 - PHP
foreach ($result_array as $key => $value)
{
echo $value \n;
}
Just SELECT * FROM table_name WHERE.... will do the trick.
To grab data from specific fields, it would be SELECT field_1,field_2,field_3....
you have to make a string which represent mysql query. Then there is function in php named mysql_query(). Call this function with above string as parameter. It will return you all results. Here are some examples
You need to do it like this...
First connect to your sql... Reference
Now make a query and assign it to a variable...
$query = mysqli_query($connect, "SELECT column_name1, column_name2 FROM tablename");
If you want to retrieve a single row use LIMIT 1
$query = mysqli_query($connect, "SELECT column_name1, column_name2 FROM tablename LIMIT 1");
If you want to fetch all the columns just use * instead of column names and if you want to leave some rows where specific column data is blank you can do it like this
$query = mysqli_query($connect, "SELECT * FROM tablename WHERE column_name4 !=''");
Now fetch the array out of it and loop through the array like this..
while($show_rows = mysqli_fetch_array($query)) {
echo $show_rows['column_name1'];
echo $show_rows['column_name2'];
}
If you don't want to include the column names in the while loop, you could do this:
while($show_rows = mysqli_fetch_array($query)) {
foreach( $show_rows as $key => $val )
{
echo $show_rows[$key];
}
}
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);
}
}
I want to generate an array of colnames after performing a query.
$sql = "SELECT prename, lastname, CONCAT (prename, ' ', lastname AS name)
FROM mytable WHERE ... ";
$result = mysqli_query($con,$sql);
$row = mysqli_fetch_assoc($result);
foreach ( $row as $key => $value ) $colNames[] = $key;
I know that I can get the colnames of a table using
$sql = "SHOW COLUMNS FROM mytable;
But how can I get colnames, that are created using MySql functions like "CONCAT ... " if the query-result is empty?
Therefore my question:
Is it possible to get the column names of a query that returns an empty result?
Is it possible to get the column names of a query that returns an empty result?
No, it is not possible because when you get the results you receive an associative array with keys<=>values. So if you receive an empty result there are no values, and if there are no values, there is no associative array to get the keys from.
If you are trying to write a minimalist block of code, you might want to try another approach. But you all ready wrote the answer: $sql = "SHOW COLUMNS FROM mytable; and it probably takes 0.0001 secs so...
FROM php.net/...mysql_fetch_assoc()
mysql_fetch_assoc
Return Values:
Returns an associative array of strings that corresponds to the fetched row, or FALSE if there are no more rows.
In my app, the user can type in an indefinite amount of categories to search by. Once the user hits submit, I am using AJAX to call my PHP script to query my DB and return the results that match what the user defined for the categories.
My category column is separated as so for each row: "blue,red,yellow,green" etc.
I have two questions:
How can I pass an array to MySQL (like so: [blue,yellow,green]) and then search for each term in the categories column? If at-least one category is found, it should return that row.
Can MySQL add weight to a row that has more of the categories that the user typed in, therefor putting it further to the top of the returned results? If MySQL cannot do this, what would be the best way to do this with PHP?
Thanks for taking the time and looking at my issue.
For the part 1 you can use the function below:
<?php
function createquery($dataarray){
$query="select * from table where ";
$loop=1;
foreach($dataarray as $data)
{
$query.="col='$data'";
if(count($dataarray)<$loop-1){
$query.=' or ';
}
$loop++;
}
return $query;
}
?>
This will return the long query.
use this some like this:
mysql_query("select * from table where category in (".implode($yourarray,',').")");
1)
Arrays are not passed to a MySQL database. What's past is a query which is a string that tells the database what action you want to preform. An example would be: SELECT * FROM myTable WHERE id = 1.
Since you are trying to use the values inside your array to search in the database, you could preform a foreach loop to create a valid SQL command with all those columns in PHP, and then send that command / query to the database. For example:
$array = array('blue', 'red', 'yellow', 'green');
$sql = "SELECT ";
foreach ($array as $value)
{
$sql .= $value.", ";
}
$sql .= " FROM myTable WHERE id = 1";
IMPORTANT! It is highly recommended to used prepared statements and binding your parameters in order not to get hacked with sql injection!
2)
You are able to order the results you obtained in whichever way you like. An example of ordering your results would be as follows:
SELECT * FROM myTable WHERE SALARY > 2000 ORDER BY column1, column2 DESC
So I have the following mysql statement saving to an array:
$sql = "SELECT did FROM did WHERE id = '$did_id'";
$result = mysqli_query($link, $sql, MYSQLI_STORE_RESULT);
while($row = $result->fetch_row()){
$did[] = $row;
}
That part works great. But now I need to take the values in the $did array and perform another lookup using the values in it. The way it works is we have users assigned to certain did's. So I find the did's that the user is assigned to (the $did array) and only show them results from another table based on those did values. I have no idea how this part works, but this is what my next statement needs to do:
SELECT * FROM log WHERE did_id = "the values in $did array"
Hope someone can help. I really appreciate it. I haven't really been able to find anything on it.
You can use php's join with mysql's IN to make comma separated strings you can also use implode , join() is an alias of implode();
SELECT * FROM log WHERE did_id IN( ".join(',',$did).")
One thing to mention here that your $did should contains ids in manner like
array("1","2","3"....)
So in your loop fetch first index that holds did column value
$did[] = $row[0];
Note: i assume did , did_id type is int or bigint
I have a table A, with just two columns: 'id' and 'probably'. I need to go over a long list of ids, and determine for each one whether he is in A and has probability of '1'. What is the best way to do it?
I figured that it would be best to have 1 big query from A in the beginning of the script, and after that when I loop each id, I check the first query. but than i realized I don't know how to do that (efficiently). I mean, is there anyway to load all results from the first query to one array and than do in_array() check? I should mention that the first query should had few results, under 10 (while table A can be very large).
The other solution is doing a separate query in A for each id while I loop them. But this seems not very efficient...
Any ideas?
If you have the initial list of ids in array, you can use the php implode function like this:
$query = "select id
from A
where id in (".implode (',', $listOfIds).")
and probability = 1";
Now you pass the string as first parameter of mysql_query and receive the list of ids with probability = 1 that are within your initial list.
// $skip the amount of results you wish to skip over
// $limit the max amount of results you wish to return
function returnLimitedResultsFromTable($skip=0, $limit=10) {
// build the query
$query = "SELECT `id` FROM `A` WHERE `probability`=1 LIMIT $skip, $limit";
// store the result of the query
$result = mysql_query($query);
// if the query returned rows
if (mysql_num_rows($result) > 0) {
// while there are rows in $result
while ($row = mysql_fetch_assoc($result)) {
// populate results array with each row as an associative array
$results[] = $row;
}
return $results;
} else {
return false;
}
}
for each time you call this function you would need to increment skip by ten in order to retrieve the next ten results.
Then to use the values in the $results array (for example to print them):
foreach ($results as $key => $value) {
print "$key => $value <br/>";
}
Build a comma separated list with your ids and run a query like
SELECT id
FROM A
WHERE id IN (id1, id2, id3, ... idn)
AND probability = 1;
Your first solution proposal states that:
You will query the table A, probabyly using limit clause since A is a table with large data.
You will place the retrieved data in an array.
You will iterate through the array to look for the id's with probability of '1'.
You will repeat the first three steps several times until table A is iterated fully.
That is very inefficient!
Algorithm described above would require lots of database access and unneccessary memory (for the temporary array). Instead, just use a select statement with 'WHERE' clause and process with the data you want.
You need a query like the following I suppose:
SELECT id, probably FROM A WHERE A.probably = 1
If i understood you correctly, you should filter in the SQL query
SELECT * FROM A WHERE A.probably = 1