In this tutorial you will learn how to use concat_ws() String function of mysql with java servlet
Mysql CONCAT_WS() Function Example Using Java Servlet
In this tutorial you will learn how to use concat_ws() String function of mysql with java servlet
CONCAT_WS() method of mysql, concatenated strings with a separator. Separator is a string. In the parameter of this function separator string is specified as first argument and the other strings are specified as the further next arguments after separator string, these strings that will be concatenated are separated by comma (,).
Syntax :
concat_ws('separator','string1','string2'...,'stringN');
Here separator is a string, a character, special character or numbers.
Now, since I have to use this function in java servlet program, therefore I have created a java servlet class named MysqlConcatWsServlet 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 am passing the query "SELECT CONCAT_WS("+"'"+str+"'"+","+"'"+str1+"'"+","+"'"+str2+"'"+")"; (This query will return the output after adding the strings with separator. Here str, str1, str2 are the variables that stores the value given by the user.) 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 :
ConcatWs.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>Concatenate strings with separator</title> </head> <body> <form method="get" action="MysqlConcatWsServlet"> <table><tr><td>Enter a string to separate two string</td><td><input type="text" name="txtName"/></td></tr> <tr><td align="left">Enter first string</td><td><input type="text" name="txtName1"/></td></tr> <tr><td align="left">Enter second string</td><td><input type="text" name="txtName2"/></td></tr> <tr><td align="center"><input type="submit" value="CLICK here to Concatenate Strings"/> </table> </form> </body> </html>
MysqlConcatWsServlet.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 MysqlConcatWsServlet extends HttpServlet
{
String str, str1, str2;
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws IOException, ServletException
{
response.setContentType("text/html");
PrintWriter out = response.getWriter();
str= request.getParameter("txtName");
str1= request.getParameter("txtName1");
str2= request.getParameter("txtName2");
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 concat_ws("+"'"+str+"'"+","+"'"+str1+"'"+","+"'"+str2+"'"+")";
ps=con.prepareStatement(sql);
rs=ps.executeQuery();
while(rs.next())
{
sql= rs.getString(1);
out.println(sql);
}
}
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>MysqlConcatWsServlet</servlet-name> <servlet-class>MysqlConcatWsServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>MysqlConcatWsServlet</servlet-name> <url-pattern>/MysqlConcatWsServlet</url-pattern> </servlet-mapping> </web-app>
Output
When you will execute the above example you will get the output as :
1.
2. When you will enter the strings.
3. Output when you will click on click button.
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