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The SQL SELECT statement is used to select the records from database tables.
Syntax :
The basic syntax of the
select clause is –
To select all columns from the table, the
Implementation of the Select Query :
Let us consider the following table ‘ Data ‘ with three columns ‘ FirstName ‘, ‘ LastName ‘ and ‘ Age ‘.
To select all the data stored in the ‘ Data ‘ table, we will use the code mentioned below.
SELECT Query using Procedural Method :
<?php
$link = mysqli_connect("localhost", "root", "", "Mydb");
if ($link === false) {
die("ERROR: Could not connect. "
.mysqli_connect_error());
}
$sql = "SELECT * FROM Data";
if ($res = mysqli_query($link, $sql)) {
if (mysqli_num_rows($res) > 0) {
echo "<table>";
echo "<tr>";
echo "<th>Firstname</th>";
echo "<th>Lastname</th>";
echo "<th>age</th>";
echo "</tr>";
while ($row = mysqli_fetch_array($res)) {
echo "<tr>";
echo "<td>".$row['Firstname']."</td>";
echo "<td>".$row['Lastname']."</td>";
echo "<td>".$row['Age']."</td>";
echo "</tr>";
}
echo "</table>";
mysqli_free_result($res);
}
else {
echo "No matching records are found.";
}
}
else {
echo "ERROR: Could not able to execute $sql. "
.mysqli_error($link);
}
mysqli_close($link);
?>
Output :
Code Explanation:
- The “res” variable stores the data that is returned by the function mysql_query().
- Everytime mysqli_fetch_array() is invoked, it returns the next row from the res() set.
- The while loop is used to loop through all the rows of the table “data”.
SELECT Query using Object Oriented Method :
<?php
$mysqli = new mysqli("localhost", "root", "", "Mydb");
if ($mysqli === false) {
die("ERROR: Could not connect. "
.$mysqli->connect_error);
}
$sql = "SELECT * FROM Data";
if ($res = $mysqli->query($sql)) {
if ($res->num_rows > 0) {
echo "<table>";
echo "<tr>";
echo "<th>Firstname</th>";
echo "<th>Lastname</th>";
echo "<th>Age</th>";
echo "</tr>";
while ($row = $res->fetch_array())
{
echo "<tr>";
echo "<td>".$row['Firstname']."</td>";
echo "<td>".$row['Lastname']."</td>";
echo "<td>".$row['Age']."</td>";
echo "</tr>";
}
echo "</table>";
$res->free();
}
else {
echo "No matching records are found.";
}
}
else {
echo "ERROR: Could not able to execute $sql. "
.$mysqli->error;
}
$mysqli->close();
?>
Output :
SELECT Query using PDO Method :
<?php
try {
$pdo = new PDO("mysql:host = localhost;
dbname=mydb", "root", "");
$pdo->setAttribute(PDO::ATTR_ERRMODE,
PDO::ERRMODE_EXCEPTION);
}
catch (PDOException $e) {
die("ERROR: Could not connect. ".$e->getMessage());
}
try {
$sql = "SELECT * FROM Data";
$res = $pdo->query($sql);
if ($res->rowCount() > 0) {
echo "<table>";
echo "<tr>";
echo "<th>Firstname</th>";
echo "<th>Lastname</th>";
echo "<th>Age</th>";
echo "</tr>";
while ($row = $res->fetch()) {
echo "<tr>";
echo "<td>".$row['Firstname']."</td>";
echo "<td>".$row['Lastname']."</td>";
echo "<td>".$row['Age']."</td>";
echo "</tr>";
}
echo "</table>";
unset($res);
}
else {
echo "No matching records are found.";
}
}
catch (PDOException $e) {
die("ERROR: Could not able to execute $sql. "
.$e->getMessage());
}
unset($pdo);
?>
Output :