I'd like to simplify how my app builds a query and loops through the results. Most of the actual code works, except that PHP does not display all of the results fetched from my query.
PREFACE: example code ahead, do not use in production.
First I build the query.
$arr_fields = array('color', 'number', 'size');
$select_fields = implode(', ', $arr_fields);
$q = "SELECT $select_fields FROM supplychain";
Now I execute the query then loop through the result set.
Pro tip: don't use this code for anything important - it's for demo purposes only.
echo "<table>";
$res = doQuery($q);
// create report body
foreach($res as $r)
{
// set values from array of field names
$row_fields = '';
foreach ($arr_fields as $f)
{
// set current $arr_field value inside a table cell...
$row_fields.= "<td>$r[$f]</td>";
}
// display the row
echo "<tr>$row_fields</tr>";
}
echo "</table>";
The first database value from $arr_fields (color) is output as expected, the rest are not.
The assembled query issued at a MySQL console shows values for color, number and size. There aren't any SQL errors generated by the script.
Why is PHP displaying the first field's value but skipping the other two?
The issue turned out to be a space before each of the fieldnames in my array (not shown in the example above).
The field array actually was
$arr_fields = array('color', ' number', ' size');
Once I removed the spaces, values showed up as usual. Thanks for Norbert for helping point me in the right direction via additional testing.
Change this line:
$row_fields.= "<td>$r[$f]</td>";
to:
$row_fields.= "<td>".$r[$f]."</td>";
Related
I am using PDO to execute a query for which I am expecting ~500K results. This is my query:
SELECT Email FROM mytable WHERE flag = 1
When I run the query in Microsoft SQL Server management Studio I consistently get 544838 results. I wanted to write a small script in PHP that would fetch these results for me. My original implementation used fetchAll(), but this was exhausting the memory available to php, so I decided to fetch the results one at a time like so:
$q = <<<QUERY
SELECT Email FROM mytable WHERE flag = 1
QUERY;
$stmt = $conn->prepare($q);
$stmt->execute();
$c = 0;
while ($email = $stmt->fetch()[0]) {
echo $email." $c\n";
$c++;
}
but each time I run the query, I get a different number of results! Typical results are:
445664
445836
445979
The number of results seems to be short 100K +/- 200 ish. Any help would be greatly appreciated.
fetch() method fetches one row at a time from current result set. $stmt->fetch()[0] is the first column of the current row.
Your sql query has no ordering and can have some null or empty values (probably).
Since you are controlling this column value in while loop, if the current row's first value is null, it will exit from the loop.
Therefore, you should control only fetch(), not fetch()[0] or something like that.
Also, inside the while loop, use sqlsrv_get_field() to access the columns by index.
$c = 0;
while ($stmt->fetch()) { // You may want to control errors
$email = sqlsrv_get_field($stmt, 0); // get first column value
// $email can be false on errors
echo $email . " $c\n";
$c++;
}
sqlsrv_fetch
So the problem that I am encountering is that I have a select field that is populated via PHP. A MySQL DB is queried and the PHP processes the returned array, printing it into the select field's options.
However, when a single result is returned from the DB, only the first character of the string is displayed. If multiple results are returned, then all results display fully. I have checked that when a single result is returned, that the string itself is correct, which it is, so I don't believe this to be an issue with the data retrieval. Furthermore, no errors are generated either, so no clues are provided as to where things are going wrong.
I've tried to find other StackOverflow posts describing this issue, but haven't found anything, nor can I find anything elsewhere on the internet.
This is the DB Stored Procedure that collects the results:
BEGIN
SELECT BranchID, City FROM Branch;
END
Then this PHP turns that data into an associative array:
$result = $currentconnection->DBQuery("CALL Fetch_Branch_City_All()");
if( !$result) die($mysql->error);
while($row = $result->fetch_assoc()){
$BranchID = $row["BranchID"];
$CityName = $row["City"];
$results = $this->array_push_assoc($results, 'BranchID', $BranchID);
$results = $this->array_push_assoc($results, 'CityName', $CityName);
}
This is a go-between piece of code that calls the function above and makes it available to the code below, via the $Query variable.
$Query = $pModel->fetchBranchCity();
And finally this code creates the select from the array data:
<?php //Note if only one branch in system, displays single character
extract($Query, EXTR_OVERWRITE);
for ($a = 0; $a < count($BranchID); ++$a) {
if($BranchID[$a] == $BranchIDText){ ?>
<option value="<?=$BranchID[$a]?>" selected="selected"> <?=$CityName[$a]?> </option>
<?php }else{ ?>
<option value="<?=$BranchID[$a]?>"> <?=$CityName[$a]?> </option>
<?php }
}
?>
It has to do with the extract, while the $result is always an array, the $BranchID and $CityName aren't always.
So when they have one value, they aren't arrays, just strings and looping through them extracts the characters instead of the whole string from an array.
Please do tell me if you need help handling this exception in code.
hints: is_array
I'm running a PDO query, something like:
$inputArr = array(val1, val2, val3, ...);
$qMarks = str_repeat('?,', count($inputArr) - 1) . '?';
$stmt = $db->prepare("SELECT id, name, type, level
FROM table
WHERE name IN ($qMarks)");
$stmt->execute($inputArr);
... parse the rows that have been returned
And this works exactly as expected, no hang-ups or anything.
My problem is that I need to know which value from $inputArr was used to get each row returned.
I've tried
WHERE name IN ($qMarks) AS inputVal
and
WHERE name IN ($qMarks AS inputVal)
but those crash the query.
How can I determine which input array value was used to return each row in the output?
EDIT 1
Yes, I understand that the input search value would be name, for this particular case, but the query above is only for demonstration purposes of how I am putting the search values into the query.
The actual is much more complex, and returns any name value with is close (but not always identical).
The AS keyword is not going to work as you expect it. It's mainly used for aliasing subqueries. You can't (to my knowledge) use it in a WHERE clause.
The scenario you've outlined should have the 'name' in $row['name']. If it was a different variable that you wanted to see, you'd simply add it in your SELECT clause.
Great question, and simple answer:
The WHERE name IN $qMarks)"); part of your code is only obtaining the values in your database that are matching your array, so what you can do is see which values of name are present in the row you fetched. For example:
$rows_fetched = $stmt->fetchAll(PDO::FETCHASSOC);
$inputArray = array();
foreach($rows_fetched as $value)
{
$inputArray[] = $value['name'];
}
print_r($inputArray);//printing the results
Now you have the array $inputArray with all the values used to return each row in the output. Let me know if that worked for you!
I seem to be having trouble understanding the concept of how to properly use the information in a MySQL database using PHP/MySQLi. As I understand it, you generate a variable representing the connection object:
$connectionObject = mysqli_connect('serverString', 'userString', 'passString', 'databaseString');
then, generate a variable representing the query string you want to use:
$queryString = "SELECT rowName FROM tableName";
then, generate a variable representing the result object returned from a successful query:
$resultObject = mysqli_query($connectionObject, $queryString);
then, you use the fetch_assoc() function to generate an array from the result object and assign it to a variable:
$resultArray = myqli_fetch_assoc($resultObject);
then, you can use a while loop to (I have trouble with this one) to sort through the array and use the content of the row somehow:
while ($resultArray) {
echo $resultArray["rowName"];
}
Do I have this concept the wrong way, somehow, because its just not working for me, even to output the text content of a text-based CHAR(10) field with the contents of no more than: "BLAH".
The need to loop through the array to pick out the array item by name in the end anyway seems moot to me to begin with, but no matter where I look, I find the same concept.
My script code, minus a few key details, is:
if ($connectionObject=mysqli_connect("host0", "username0", "password0", "mysqldatabase0")) {
echo "Con";
}
if ($queryString="SELECT 'testdata' FROM 'testtable'") {
echo "Query";
}
if ($resultObject=mysqli_query($connectionObject, $queryString)) {
echo "Result";
}
if ($resultArray=mysqli_fetch_assoc($resultObject)) {
echo "Array";
}
while ($row=$resultArray) {
echo $row["testdata"];
print_r ($row);
}
mysqli_fetch_assoc returns an associate array of string representing the fetched row in the result set which is your $resultObject.
The problem is where you're using the while loop. You want to capture the returned associative array in a variable and access your data via that variable like follows:
while ($row = $resultArray) {
echo $row["rowName"];
}
To sort by rowName you can use the mysql order by clause in your query like follows which returns your results sorted by rowName:
$queryString = "SELECT rowName FROM tableName order by rowName";
Update after OP posted full code:
In your first if statement what would happen if the connection failed? You want to add some error handling there:
$connectionObject=mysqli_connect("host0", "username0", "password0", "mysqldatabase0"));
if (!$connectionObject) {
// exist out of this script showing the error
die("Error connecting to database " . mysqli_error($connectionObject));
} else {
// Don't really need this else but I'll keep it here since you already had it
echo "Con";
}
The problem is here You are using single quotes for column name and table name which are mysql identifiers. MySQL identifiers quote character is backtick not single quote.
Basically you need to use backticks if one of these identifiers are one of mysql reserved words (MySQL Reserved words), for other cases you don't need to use them.
Update your query:
if ($queryString="SELECT `testdata` FROM `testtable`") {
echo "Query"; // Leaving as is, not required
}
Lastly, an improvement. You want to add error handling here too:
if ($resultObject=mysqli_query($connectionObject, $queryString)) {
echo "Result"; // Leaving as is, not required
} else {
echo "Error executing Query " . mysqli_error($connectionObject);
}
Please note that when you use this script the error messages will be printed at the client i.e. when you use this script in a web application the errors will be shown in the user's browser. So you want to look into implementing logging and not printing them directly.
mysqli_fetch_assoc() returns one row as an associative array, of a mysqli_result object. Each time it is called, it returns the next row of results automatically and when used with a while loop, can be used to fetch an unknown number of result rows.
The $row['columnName'] is used to refer to the column. For example, if you had a person object with columns firstName, lastName, dateOfBirth, you could iterate through each person with a while loop as such:
while($row=mysqli_fetch_assoc($resultObject)){
$fname = $row['firstName'];
$lname = $row['lastName'];
$dob = $row['dateOfBirth'];
echo $fname . ' ' . $lname . ' ' . $dob;
}
This will echo details for a result returning an unknown amount of people.
Remember, calling the
if ($resultArray=mysqli_fetch_assoc($resultObject)) {
echo "Array";
}
before the while loop will skip the first result, so make sure the query returns multiple results when testing, as if you are only providing a resultObject containing one result, this might be why it isn't returning anything.
A better way to check if any results are returned is with the mysqli_num_rows($resultObject) function.
if(mysqli_num_rows($resultObject) > 0){
echo "Array";
}
Also not sure if it was just a typo but just to be sure, in your query you are selecting columnName not rowName:
$queryString = "SELECT columnName1(eg. firstName), columnName2(eg. lastName) FROM tableName";
I just recently started learning PHP, and the mysqli_fetch_assoc function confused me too, so I hope this helps!
I have one problem here, and I don't even have clue what to Google and how to solve this.
I am making PHP application to export and import data from one MySQL table into another. And I have problem with these tables.
In source table it looks like this:
And my destination table has ID, and pr0, pr1, pr2 as rows. So it looks like this:
Now the problem is the following: If I just copy ( insert every value of 1st table as new row in second) It will have like 20.000 rows, instead of 1000 for example.
Even if I copy every record as new row in second database, is there any way I can fuse rows ? Basically I need to check if value exists in last row with that ID_, if it exist in that row and column (pr2 for example) then insert new row with it, but if last row with same ID_ does not have value in pr2 column, just update that row with value in pr2 column.
I need idea how to do it in PHP or MySQL.
So you got a few Problems:
1) copy the table from SQL to PHP, pay attention to memory usage, run your script with the PHP command Memory_usage(). it will show you that importing SQL Data can be expensive. Look this up. another thing is that PHP DOESNT realese memory on setting new values to array. it will be usefull later on.
2)i didnt understand if the values are unique at the source or should be unique at the destination table.. So i will assume that all the source need to be on the destination as is.
I will also assume that pr = pr0 and quant=pr1.
3) you have missmatch names.. that can also be an issue. would take care of that..also.
4) will use My_sql, as the SQL connector..and $db is connected..
SCRIPT:
<?PHP
$select_sql = "SELECT * FROM Table_source";
$data_source = array();
while($array_data= mysql_fetch_array($select_sql)) {
$data_source[] = $array_data;
$insert_data=array();
}
$bulk =2000;
foreach($data_source as $data){
if(isset($start_query) == false)
{
$start_query = 'REPLACE INTO DEST_TABLE ('ID_','pr0','pr1','pr2')';
}
$insert_data[]=implode(',',$data).',0)';// will set 0 to the
if(count($insert_data) >=$bulk){
$values = implode('),(',$insert_data);
$values = substr(1,2,$values);
$values = ' VALUES '.$values;
$insert_query = $start_query.' '.$values;
$mysqli->query($insert_query);
$insert_data = array();
} //CHECK THE SYNTAX IM NOT SURE OF ALL OF IT MOSTLY THE SQL PART>> SEE THAT THE QUERY IS OK
}
if(count($insert_data) >=$bulk) // IF THERE ARE ANY EXTRA PIECES..
{
$values = implode('),(',$insert_data);
$values = substr(1,2,$values);
$values = ' VALUES '.$values;
$insert_query = $start_query.' '.$values;
$mysqli->query($insert_query);
$insert_data = null;
}
?>
ITs off the top off my head but check this idea and tell me if this work, the bugs night be in small things i forgot with the QUERY structure, print this and PASTE to PHPmyADMIN or you DB query and see its all good, but this concept will sqve a lot of problems..