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Thread: Where

  1. #1
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    Default Where

    Following code works until I try to add WHERE to the Query. I have no errors before run but get the errors below. I need the proper syntax or method to specify the row. HELP!!!

    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.sql.Statement;
     
     
    public class TryThree {
     
    public static void main(String args[]) throws SQLException{
     
    Connection con = DriverManager.getConnection ("jdbc:mysql://67.20.123.248:3306/whitebu4_sliditerod" ,"whitebu4_admins" , "***");
    String dbClass = "com.mysql.jdbc.Driver";
    String Nome = null;
    String query = ("Select x,y,z FROM xyz WHERE pname='" + Nome + "'");
     
    Object prepareStatement = null;
     
    ((PreparedStatement) prepareStatement).setString(1, Nome);
     
    try {
     
    Class.forName("com.mysql.jdbc.Driver");
     
    Statement st = con.createStatement();
    ResultSet rs = st.executeQuery(query);
    while(rs.next()){
    float id  = rs.getFloat("x");
    float id1  = rs.getFloat("y");
    float id2  = rs.getFloat("z");
     
    System.out.print("ID: " + id);
    System.out.print("id1 " + id1);
    System.out.print("id2 " + id2);
     
    } //end while
     
    con.close();
    } //end try
     
    catch(ClassNotFoundException e) {
    e.printStackTrace();
    }
     
    catch(SQLException e) {
    e.printStackTrace();
    }
     
    }  //end main
     
    }  //end class
    Exception in thread "main" java.lang.NullPointerException
    at TryThree.main(TryThree.java:21)

  2. #2
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    Default Re: Where

    It's because your String "Nome" is null.

    You need to give it a proper value.
    Please use [highlight=Java]//code goes here...[/highlight] tags when posting your code

  3. #3
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    Default Re: Where

    That didnt work Ive tried it developed into more errors Im now trying this which makes more sense but still produces errors. Why cant I specify a row without hassle?

    import java.sql.Connection;
    import java.sql.DriverManager;
    import java.sql.PreparedStatement;
    import java.sql.ResultSet;
    import java.sql.SQLException;
    import java.sql.Statement;
     
     
    public class TryThree {
     
    public static void main(String args[]) throws SQLException{
     
    Connection con = DriverManager.getConnection ("jdbc:mysql://67.20.123.248:3306/whitebu4_sliditerod" ,"whitebu4_admins" , "admins1234");
    String dbClass = "com.mysql.jdbc.Driver";
    Statement statement = con.createStatement();
    String query = "Select x,y,z FROM xyz";
    ResultSet result = statement.executeQuery(query);
     
    result.getFloat    ("Nome");
    result.getFloat   ("Nome");
    result.getFloat    ("Nome");
    result.getString    ("Nome");
     
     
     
    try {
     
    Class.forName("com.mysql.jdbc.Driver");
     
    Statement st = con.createStatement();
     
    while(result.next()){
     
     
    System.out.print(result);
    System.out.print(result);
    System.out.print(result);
     
    } //end while
     
    con.close();
    } //end try
     
    catch(ClassNotFoundException e) {
    e.printStackTrace();
    }
     
    catch(SQLException e) {
    e.printStackTrace();
    }
     
    }  //end main
     
    }  //end class

  4. #4
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    Default Re: Where

    You've converted your small problem into a heap of problems I imagine.
    Please be more direct with your questions and provide more information of what is going wrong.
    Please use [highlight=Java]//code goes here...[/highlight] tags when posting your code

  5. #5
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    Default Re: Where

    How can I specify a Row to select data from using a string for the choice??