Select and Filter Data From a MySQL Database #
MySQL мэдээллийн сангаас өгөгдлийг сонгож, шүүх #
The WHERE clause is used to filter records.
WHERE өгүүлбэрийг бичлэгийг шүүхэд ашигладаг.
The WHERE clause is used to extract only those records that fulfill a specified condition.
WHERE заалтыг зөвхөн заасан нөхцлийг хангасан бичлэгийг задлахад ашигладаг.
SELECT column_name(s) FROM table_name WHERE column_name operator value
To learn more about SQL, please visit our SQL tutorial.
SQL-ийн талаар илүү ихийг мэдэхийг хүсвэл манай SQL заавраар зочилно уу.
Select and Filter Data With MySQLi #
MySQLi ашиглан өгөгдлийг сонгоод шүүнэ үү
The following example selects the id, firstname and lastname columns from the MyGuests table where the lastname is “Doe”, and displays it on the page:
Дараах жишээ нь MyGuests хүснэгтээс овог нь “Doe” байгаа id, namename, lastname багануудыг сонгоод хуудсан дээр харуулна:
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}
$sql = "SELECT id, firstname, lastname FROM MyGuests WHERE lastname='Doe'";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
// output data of each row
while($row = $result->fetch_assoc()) {
echo "id: " . $row["id"]. " - Name: " . $row["firstname"]. " " . $row["lastname"]. "<br>";
}
} else {
echo "0 results";
}
$conn->close();
?>
Code lines to explain from the example above:
Дээрх жишээнээс тайлбарлах кодын мөрүүд:
First, we set up the SQL query that selects the id, firstname and lastname columns from the MyGuests table where the lastname is “Doe”. The next line of code runs the query and puts the resulting data into a variable called $result.
Нэгдүгээрт, MyGuests хүснэгтээс овог нь “Doe” байгаа id, namename, lastname багануудыг сонгох SQL query-г тохируулсан. Дараагийн код мөр нь асуулга ажиллуулж, өгөгдлийг $ result нэртэй хувьсагч руу оруулна.
Then, the function num_rows() checks if there are more than zero rows returned.
Дараа нь function num_rows() буцааж тэгээс их мөр байгаа эсэхийг шалгана.
If there are more than zero rows returned, the function fetch_assoc() puts all the results into an associative array that we can loop through. The while() loop loops through the result set and outputs the data from the id, firstname and lastname columns.
Хэрэв тэгээс дээш мөрийг буцааж өгвөл fetch_assoc() функц нь бүх үр дүнг ассоциатив массивт оруулдаг. while() давталт нь үр дүнгийн багцыг тойрон эргэлдэж id, namename, namen багануудаас өгөгдлийг гаргана.
The following example shows the same as the example above, in the MySQLi procedural way:
Дараах жишээг дээрх жишээний нэгэн адил MySQLi процедурын аргаар харуулав:
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// Create connection
$conn = mysqli_connect($servername, $username, $password, $dbname);
// Check connection
if (!$conn) {
die("Connection failed: " . mysqli_connect_error());
}
$sql = "SELECT id, firstname, lastname FROM MyGuests WHERE lastname='Doe'";
$result = mysqli_query($conn, $sql);
if (mysqli_num_rows($result) > 0) {
// output data of each row
while($row = mysqli_fetch_assoc($result)) {
echo "id: " . $row["id"]. " - Name: " . $row["firstname"]. " " . $row["lastname"]. "<br>";
}
} else {
echo "0 results";
}
mysqli_close($conn);
?>
<?php
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDB";
// Create connection
$conn = new mysqli($servername, $username, $password, $dbname);
// Check connection
if ($conn->connect_error) {
die("Connection failed: " . $conn->connect_error);
}
$sql = "SELECT id, firstname, lastname FROM MyGuests WHERE lastname='Doe'";
$result = $conn->query($sql);
if ($result->num_rows > 0) {
echo "<table><tr><th>ID</th><th>Name</th></tr>";
// output data of each row
while($row = $result->fetch_assoc()) {
echo "<tr><td>".$row["id"]."</td><td>".$row["firstname"]." ".$row["lastname"]."</td></tr>";
}
echo "</table>";
} else {
echo "0 results";
}
$conn->close();
?>
Select Data With PDO (+ Prepared Statements) #
PDO ашиглан өгөгдлийг сонгох (+ Бэлтгэсэн мэдэгдэл) #
The following example uses prepared statements.
Дараах жишээнд бэлтгэсэн мэдэгдлийг ашиглав.
It selects the id, firstname and lastname columns from the MyGuests table where the lastname is “Doe”, and displays it in an HTML table:
Энэ нь MyGuests хүснэгтээс овог “Doe” байгаа id, namename, lastname багануудыг сонгож HTML хүснэгтэд харуулна.
Example Жишээ (PDO) #
<?php
echo "<table style='border: solid 1px black;'>";
echo "<tr><th>Id</th><th>Firstname</th><th>Lastname</th></tr>";
class TableRows extends RecursiveIteratorIterator {
function __construct($it) {
parent::__construct($it, self::LEAVES_ONLY);
}
function current() {
return "<td style='width:150px;border:1px solid black;'>" . parent::current(). "</td>";
}
function beginChildren() {
echo "<tr>";
}
function endChildren() {
echo "</tr>" . "\n";
}
}
$servername = "localhost";
$username = "username";
$password = "password";
$dbname = "myDBPDO";
try {
$conn = new PDO("mysql:host=$servername;dbname=$dbname", $username, $password);
$conn->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_EXCEPTION);
$stmt = $conn->prepare("SELECT id, firstname, lastname FROM MyGuests WHERE lastname='Doe'");
$stmt->execute();
// set the resulting array to associative
$result = $stmt->setFetchMode(PDO::FETCH_ASSOC);
foreach(new TableRows(new RecursiveArrayIterator($stmt->fetchAll())) as $k=>$v) {
echo $v;
}
}
catch(PDOException $e) {
echo "Error: " . $e->getMessage();
}
$conn = null;
echo "</table>";
?>
