Monday, May 24, 2010

Count Rows from a Database Table

After creating a database table, if we want to know number of rows in a table then we can get it very easily by using the simple database query. See brief description below:

Description of program:

For this program to work firstly we need to establish the connection with MySQL database by the help of JDBC driver. When the connection has been established we need to pass a table name from the given database in the query and the rows will be counted and the result will be displayed. If any exception is thrown then it will show "SQL statement is not executed!"

Description of code:

SELECT COUNT(*) FROM table_name;
This code is used to count the rows of given table.
table_name: It is a name of the table of which we want to see the rows.

Here is the code of program:

import java.io.*;
import java.sql.*;

public class CountRows{
public static void main(String[] args) {
System.out.println("Count number of rows in a specific table!");
Connection con = null;
int count = 0;
try{
Class.forName("com.mysql.jdbc.Driver");
con = DriverManager.getConnection
("jdbc:mysql://localhost:3306/jdbctutorial","root","root");
try{
Statement st = con.createStatement();
BufferedReader bf = new BufferedReader(new InputStreamReader(System.in));
System.out.println("Enter table name:");
String table = bf.readLine();
ResultSet res = st.executeQuery("SELECT COUNT(*) FROM "+table);
while (res.next()){
count = res.getInt(1);
}
System.out.println("Number of column:"+count);
}
catch (SQLException s){
System.out.println("SQL statement is not executed!");
}
}
catch (Exception e){
e.printStackTrace();
}
}
}

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