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Mysql STRCMP() Function Example Using Java Servlet

Posted in : Java Posted on : September 30, 2011 at 8:21 PM Comments : [ 0 ]

STRCMP() function of Mysql compares the two strings order and returns the integer value either 0, 1, or -1 according to either if order of both strings are equal, if the first string is greater than the second string, or if the first string is smaller than the second

Mysql STRCMP() Function Example Using Java Servlet

In this tutorial you will learn how to use strcmp() String function of mysql with java servlet.

STRCMP() function of Mysql compares the two strings order and returns the integer value either 0, 1, or -1 according to either if order of both strings are equal, if the first string is greater than the second string, or if the first string is smaller than the second string respectively. These two strings are passed as an argument of this function

Syntax :

strcmp('str1', 'str2');

Here "str1" and "str1" are the strings variable that are taken as argument.

Now, since I have to use this function in java servlet program, therefore I have created a java servlet class named MysqlStrCmpServlet which extends the HttpServlet class. In the body of class I overridden the method doGet() and created an objects of HttpServletRequest and HttpServletResponse into its parameter. Inside the doGet() method first I set the mime type that in which format the browser will show the output. In the next line I used the getWriter() method of ServletResponse interface with the object of HttpServletResponse. HttpServletResponse interface extends this method from the ServletResponse. In Next step I am taking inputs using the getParameter() method of ServletRequest with the object of HttpServletRequest. In continue we have to establish a connection between java code and database system. So, since I am using Mysql in the example given below therefore, I am loading the driver of mysql and make a connection by using the getConnection() method of DriverManager class. It returns a Connection. Further I passed the query in my java code "SELECT STRCMP(" + "'" + str1 + "'"+","+ "'" + str2 + "'" +")"; (Here 'str1', 'str2' are variables that stores the value given by the user in their respective textfields.) into the parameter of prepareStatement() method of Connection interface which gives an object of PreparedStatement interface. In the next line I used the executeQuery() method of PreparedStatement interface which returns a ResultSet object that holds the result of query. At last I have extracted the result from the ResultSet object.

Example :

strcmp.html

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
<title>STRCMP FUNCTION</title>
</head>
<body>
<form action="MysqlStrCmpServlet" method="get">
<table>
<tr>
<td>Enter First String </td>
<td><input type="text" name="text1"/></td>
</tr>
<tr>
<td>Enter Second String </td>
<td><input type="text" name="text2"/></td>
</tr>
<tr>
<td></td>
<td><input type="submit" value="submit"/></td>
</tr>
</table>
</form>
</body>
</html>

MysqlStrCmpServlet.java

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.SQLException;
import java.sql.DriverManager;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class MysqlStrCmpServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException {
response.setContentType("text/html");
PrintWriter out = response.getWriter();

String str1 = request.getParameter("text1");
String str2 = request.getParameter("text2");

String className = "com.mysql.jdbc.Driver";
String url = "jdbc:mysql://192.168.10.13";
String user = "root";
String password = "root";

Connection con;
PreparedStatement ps;
ResultSet rs;

try {
Class.forName(className);
con = DriverManager.getConnection(url, user, password);

String sql = "SELECT STRCMP(" + "'" + str1 + "'"+","+ "'" + str2 + "'" +")";
ps = con.prepareStatement(sql);
rs = ps.executeQuery();

while (rs.next()) {
int num = Integer.parseInt((String) rs.getString(1));
if(num==0)
out.println("Both strings are same");
else if(num==-1)
out.println("First string is smaller than the second");
else
out.println("First string is greater than the second");
} 
} catch (SQLException sx) {
out.println(sx);
} catch (ClassNotFoundException cx) {
out.println(cx);
}
}
}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app id="WebApp_ID" version="2.4" xmlns="http://java.sun.com/xml/ns/j2ee" 
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<display-name>mysqlStringFunction</display-name>
<servlet>
<servlet-name>MysqlStrCmpServlet</servlet-name>
<servlet-class>MysqlStrCmpServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>MysqlStrCmpServlet</servlet-name>
<url-pattern>/MysqlStrCmpServlet</url-pattern>
</servlet-mapping>

</web-app>

Output

1. When you will execute the above example you will get the output as :