This question already has answers here:
Row count with PDO
(21 answers)
Closed 6 years ago.
I have a SELECT query, like this:
$stmnt = $conn->prepare("SELECT post_title, posts_cat FROM posts WHERE posts_cat=:posts_cat");
$stmnt->execute(array(':posts_cat' => $cat_id));
$post_info = $stmnt->fetch();
$count = $stmnt->rowCount();
If there are no posts it shows none, but if there's one or more then it displays only one.
Can someone tell me why this is?
PDOStatement::rowCount() returns the number of rows affected by the last DELETE, INSERT, or UPDATE statement executed by the corresponding PDOStatement object.
rowCount() is not for a SELECT query, use a separate COUNT query for that or fetch all rows in an array and count its size
Please do not use rowCount() with select query
use a different query with count() for counting rows
$sql = "SELECT count(*) FROM `posts` WHERE posts_cat = :posts_cat";
$stmnt = $conn->prepare($sql);
$stmnt->execute(array(':posts_cat' => $cat_id));
$count = $stmnt->fetchColumn();
Of course you are getting the right number of rows returned. 1 means that only one row was found. If you want more rows to be found, add more rows to your database to match the condition.
Whether you need such a function at all - is another question, already answered in this post
Related
This question already has answers here:
Row count with PDO
(21 answers)
MySQL - count total number of rows in php
(11 answers)
Closed 3 years ago.
Need the number of rows of a table.
$st = $db->query("select count(*) from images");
$total = $st->rowCount();
echo $total;
result - 1
The table images has 2430 rows.
How to get the correct number of rows?
using PDO you could use
$result = $con->prepare("select count(*) from images");
$result->execute();
$total = $result->fetchColumn();
echo $total;
assuming $con is your connection to db
from PHP doc
DOStatement::rowCount() returns the number of rows affected by the
last DELETE, INSERT, or UPDATE statement executed by the corresponding
PDOStatement object.
If the last SQL statement executed by the associated PDOStatement was
a SELECT statement, some databases may return the number of rows
returned by that statement. However, this behaviour is not guaranteed
for all databases and should not be relied on for portable
applications.
Using PHP and MYSQLi functions
$query = "select * from images";
$result = mysqli_query($db, $query);
echo mysqli_num_rows($result);
This will output the total number of rows in the table
Of Course this presupposes that a connection has already been established to the database using $db
This question already has answers here:
Count rows from results of a "mysql_query"
(9 answers)
MySQL - count total number of rows in php
(11 answers)
count number of rows in table using php
(6 answers)
How can I count the numbers of rows that a MySQL query returned?
(12 answers)
PHP SQL get SELECT COUNT(user) to variable
(5 answers)
Closed 4 years ago.
I have a database table timestamps_sessions containing timestamps of when a user begins an exercise on my webpage, and which is only updated when the user actually finishes it. Therefore, every row always has a value in the started column, but not always in the finished column. The latter is NULL by default.
My SELECT COUNT() statement works perfectly when I query it in Sequel Pro, and returns the correct integer of 11. That is to say: there are indeed only eleven rows that have values in both started and finished.
Yet when I execute it in PHP, it returns an object containing
{
current_field: null,
field_count: null,
lengths: null,
num_rows: null,
type: null
}
The statement I successfully query in Sequel Pro is the following:
SELECT COUNT(finished) FROM timestamps_sessions
The statement I unsuccessfully use in PHP is the following:
$sql = "SELECT COUNT(finished) FROM timestamps_sessions";
$result = $conn->query($sql);
$exercise['clears'] = $result;
There are several other SELECT queries being performed to the same database and same table without issue. It's only the COUNT() statement that seems to be malfunctioning.
What am I doing wrongly, and how should I do it instead?
My goal is to count the number of rows with a non-empty finished column, without passing on the actual data in order to preserve bandwidth. All I need is the integer.
First of all, $result is an object as expected. It's the result returned by the mysqli::query() method. Before you can access the data from this query, you need to fetch it. It will be easier if you give an alias to the count, as it will become easier to access the count.
$sql = "SELECT COUNT(finished) as cnt FROM timestamps_sessions";
$result = $conn->query($sql);
$row = $result->fetch_assoc();
$exercise['clears'] = $row['cnt'];
mysqli::query() docs
mysqli::fetch_assoc() docs
you have missing code mysql_fetch_array in order to fetch first record
$sql = "SELECT COUNT(finished) totals FROM timestamps_sessions";
$result = $conn->query($sql);
$row = $result->fetch_assoc();
$total = $row['totals'];
The argument passed to the count function can be anything, since you just want the number of rows, not their data.
SELECT COUNT(1) FROM timestamps_sessions WHERE finished IS NOT NULL;
$sql = "SELECT COUNT(finished) AS count_finished FROM timestamps_sessions";
$result = $conn->query($sql);
$row = $result->fetch_assoc();
echo $exercise['clears'] = $row['count_finished'];
Give the count an alias like count_finished. Then from the result object you need to fetch the row. The row has your data in it.
Take a look at this https://www.w3schools.com/php/php_mysql_select.asp
This question already has answers here:
PDO get the last ID inserted
(3 answers)
Closed 5 years ago.
I am trying to get the last id number of Database. But It's showing only 0.
I am learning PDO. Can anyone tell me how can I do it?
if($_SERVER['REQUEST_METHOD']=='POST'){
$sql = "SELECT * FROM tablename";
$stmt = $pdo->prepare($sql);
$stmt->execute();
$row = $stmt ->fetch();
$showid = $pdo->lastInsertId();
echo $showid;
}
lastInsertId will return the ID of a row that was inserted by the same connection. You can't use it outside of that context.
The easiest way to fetch the last ID would be to run something like,
SELECT max(id) FROM tablename
If you're using this in order to work out which ID should be inserted next, consider using an auto-increment column for your ID instead.
lastInsertId() works only after a INSERT query - since you're only doing a select, it will always return string(1) = 0
So either you perform this code after an INSERT statement, or you can do the following:
$stmt = $db->query("SELECT LAST_INSERT_ID()");
$lastId = $stmt->fetchColumn();
Refering here to: PDO get the last ID inserted
Visit this thread, you'll find my samplecode provided by Corbin and much more informations on this topic.
This question already has answers here:
How to get the total number of rows of a GROUP BY query?
(11 answers)
Closed 8 years ago.
How can I return the number of counted rows with PDO?
This is my code:
$n=$dbh->prepare("SELECT count(*) FROM users_notifications WHERE userid=0 OR userid=:userid");
$n->bindParam(":userid",$userdata['id']);
$n->execute();
$notifications = count($n);
This returns just 1. Although there are 2 results when I run the query in the database: SELECT count(*) FROM users_notifications WHERE userid=0 OR userid=:userid
The count SQL function is an aggregate function that returns one row with the number of rows matching the where clause.
PHP's count returns the number of rows in a result set, which, as illustrated in the previous paragraph, should be one. Instead, you should retrieve the value of the result column. E.g.:
$n=$dbh->prepare("SELECT count(*) as c FROM users_notifications WHERE userid=0 OR userid=:userid");
$n->bindParam(":userid",$userdata['id']);
$n->execute();
$result = $n->fetch(PDO::FETCH_ASSOC);
$notifications = $result['c'];
This question already has answers here:
Closed 10 years ago.
Possible Duplicate:
Whats the best way to get total # of records in a mysql table with php?
When i run :
mysql_query("SELECT COUNT(col) FROM table");
I end up with something like this :
(Resource) mysql result #4
How can i only get an integer that represent the number of row in my table so that later i can use it to make a simpel check such as : $result < 10.
Many Thanks
You have two options.
Get the result from the resource returned by the count query:
$resource = mysql_query("SELECT COUNT(col) FROM table");
$count = mysql_result($resource,0);
Or, get the number of rows from the resource returned by the query (without count).
$resource = mysql_query("SELECT col FROM table WHERE col IS NOT NULL");
$count = mysql_num_rows($resource);
I would recommend that you use the first, the reason being is that it is unnecessary to extract all the data from the table when you only need the count.
Note I've added WHERE col IS NOT NULL on the second one in order to recreate the effect of count(col) as opposed to count(*), as it will only count the non-null values of col.
mysql_query returns a mysql resource. To get the query output use:
$result = mysql_query("SELECT COUNT(col) FROM table");
if (!$result) {
die('Error:' . mysql_error());
}
echo mysql_result($result, 0);
See more examples here: http://php.net/manual/en/function.mysql-query.php
EDIT
By the way, this will only count the number of rows with a non-null value in col. To get the total number of rows in the table, use count(*)
Two options.
SELECT COUNT(*)....
Do the normal query. And add this line after retrieving the resource.
$num = mysql_num_rows($resource);