Mysql LEFT() function ~ Tech Blog

Tuesday, 10 July 2018

Mysql LEFT() function

Mysql LEFT()

MySQL LEFT() returns a specified number of characters from the left of the string. Both the number and the string are supplied as arguments of the function.

Syntax:

LEFT (string, length)

Arguments

Name	Description
string	The string from which a number of characters from the left are to be returned.
length	An integer which indicates the number of characters to be returned starting from the left of the string in the first argument.

MySQL Version: 5.6

Pictorial Presentation

Example of MySQL LEFT() function

The following MySQL statement returns the pub_name and 5 characters from the left of pub_name from the publisher table.

Code:

SELECT pub_name, LEFT(pub_name, 5) 
FROM publisher; 



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Sample table: publisher

Sample Output:

mysql> SELECT pub_name, LEFT(pub_name, 5) 
    -> FROM publisher;
+------------------------------+-------------------+
| pub_name                     | LEFT(pub_name, 5) |
+------------------------------+-------------------+
| Jex Max Publication          | Jex M             | 
| BPP Publication              | BPP P             | 
| New Harrold Publication      | New H             | 
| Ultra Press Inc.             | Ultra             | 
| Mountain Publication         | Mount             | 
| Summer Night Publication     | Summe             | 
| Pieterson Grp. of Publishers | Piete             | 
| Novel Publisher Ltd.         | Novel             | 
+------------------------------+-------------------+
8 rows in set (0.00 sec)

PHP script

<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>example-left-function - php mysql examples | w3resource</title>
<meta name="description" content="example-left-function - php mysql examples | w3resource">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css">
</head>
<body>
<div class="container">
<div class="row">
<div class="col-md-12">
<h2>list of publishers name and leftmost 5 characters of that name:</h2>
<table class='table table-bordered'>
<tr>
<th>Publishers name</th><th>leftmost 5 characters of Publishers name</th>
</tr>
<?php
$hostname="your_hostname";
$username="your_username";
$password="your_password";
$db = "your_dbname";
$dbh = new PDO("mysql:host=$hostname;dbname=$db", $username, $password);
foreach($dbh->query('SELECT pub_name,LEFT(pub_name,5)
FROM publisher') as $row) {
echo "<tr>"; 
echo "<td>" . $row['pub_name'] . "</td>";
echo "<td>" . $row['LEFT(pub_name,5)'] . "</td>";
echo "</tr>";
}
?>
</tbody></table>
</div>
</div>
</div>
</body>
</html>



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JSP script

<%@page contentType="text/html" pageEncoding="UTF-8"%>
<%@ page import="java.sql.*" %>
<%@ page import="java.io.*" %>
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>example-left-function</title>
</head>
<body>
<%
try {
Class.forName("com.mysql.jdbc.Driver").newInstance();
String Host = "jdbc:mysql://localhost:3306/w3resour_bookinfo";
Connection connection = null;
Statement statement = null;
ResultSet rs = null;
connection = DriverManager.getConnection(Host, "root", "datasoft123");
statement = connection.createStatement();
String Data ="SELECT pub_name,LEFT(pub_name,5) FROM publisher";
rs = statement.executeQuery(Data);
%>
<TABLE border="1">
<tr width="10" bgcolor="#9979">
<td>Publishers name</td>
<td>leftmost 5 characters of Publishers name</td>
</tr>
<%
while (rs.next()) {
%>
<TR>
<TD><%=rs.getString("pub_name")%></TD>
<TD><%=rs.getString("LEFT(pub_name,5)")%></TD>
</TR>
<%   }    %>
</table>
<%
rs.close();
statement.close();
connection.close();
} catch (Exception ex) {
out.println("Cant connect to database.");
}
%>
</body>
</html>



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Example of MySQL LEFT() function with where clause

The following MySQL statement returns the pub_name(s) who belong to the USA and 5 characters from the left of those pub_name(s) from the publisher table.

Code:

SELECT pub_name,LEFT(pub_name,5) 
FROM publisher 
WHERE country='USA'; 



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Sample table: publisher

Sample Output:

mysql> SELECT pub_name,LEFT(pub_name,5) 
    -> FROM publisher 
    -> WHERE country='USA';
+--------------------------+------------------+
| pub_name                 | LEFT(pub_name,5) |
+--------------------------+------------------+
| Jex Max Publication      | Jex M            | 
| Mountain Publication     | Mount            | 
| Summer Night Publication | Summe            | 
+--------------------------+------------------+
3 rows in set (0.00 sec)

PHP script

<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>example1-left-function - php mysql examples | w3resource</title>
<meta name="description" content="example1-left-function - php mysql examples | w3resource">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.5/css/bootstrap.min.css">
</head>
<body>
<div class="container">
<div class="row">
<div class="col-md-12">
<h2>list of publishers those who belong to USA and leftmost 5 characters of their name:</h2>
<table class='table table-bordered'>
<tr>
<th>Publishers name</th><th>leftmost 5 characters of Publishers name</th>
</tr>
<?php
$hostname="your_hostname";
$username="your_username";
$password="your_password";
$db = "your_dbname";
$dbh = new PDO("mysql:host=$hostname;dbname=$db", $username, $password);
foreach($dbh->query('SELECT pub_name,LEFT(pub_name,5)
FROM publisher
WHERE country="USA"') as $row) {
echo "<tr>";
echo "<td>" . $row['pub_name'] . "</td>";
echo "<td>" . $row['LEFT(pub_name,5)'] . "</td>";
echo "</tr>";
}
?>
</tbody></table>
></div>
</div>
</div>
</body>
</html>



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Tech Blog

Tuesday, 10 July 2018