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
character is used.
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 :
Last Updated :
26 Jul, 2022
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