checkuser.java

网上商城

package store;
import java.sql.*;
public class CheckUser {
  public CheckUser(){
     }
 public boolean userExist(String user,DBConn conn)
 {
   boolean flag=false;
   try{
     String sql = "SELECT username FROM customer WHERE username='" + user + "'";
     ResultSet rs = conn.query(sql);
     if (rs.next()) {
       flag = true;
     }
     rs.close();
   }
   catch(Exception e){
     System.out.print(e.toString());
   }
   return flag;
 }

}