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Thread: Help In JDBC

  1. #1
    juhiswt is offline Member
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    Default Help In JDBC

    I am making a program to search the student detail by enterering the roll number.In this I want to do if the student of entered roll number doest not exist in databse then it should diaplay a dialogue box The student of that roll number does not exist.
    I have used
    if(rs.wasNull())
    display the dialogue box
    else
    display the details
    but in each case else is executing but if is not why it is?

  2. #2
    Bigfatcat is offline Member
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    Could you post the code relating to the assignment of the rs (ResultSet I assume)?

    No need for the whole code block, just the bits relating to 'rs'.

  3. #3
    juhiswt is offline Member
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    Yes its result set

  4. #4
    juhiswt is offline Member
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    while(res.next())
    {
    String name=res.getString(1);
    String city=res.getString(2);
    String class1=res.getString(3);
    if(res.wasNull())
    {

    tf1.setText("Does nOt EXist");
    tf2.setText("Does nOt EXist");
    tf3.setText("Does nOt EXist");
    }
    else
    {
    tf1.setText(name);
    tf2.setText(city);
    tf3.setText(class1);
    }

    }

  5. #5
    JosAH's Avatar
    JosAH is offline Moderator
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    Read the API documentation for the ResultSet.wasNull() method; it doesn't do what you hope it does; hint, if there is no ResultSet.next() element no student matched the criteria ...

    kind regards,

    Jos
    The only person who got everything done by Friday was Robinson Crusoe.

  6. #6
    juhiswt is offline Member
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    @JosAH could u please tell me what should i use and i have read wasNull method but i can not get its use could u please tell me this also..
    Thanx

  7. #7
    JosAH's Avatar
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    Quote Originally Posted by juhiswt View Post
    @JosAH could u please tell me what should i use and i have read wasNull method but i can not get its use could u please tell me this also..
    Thanx
    If no row exists in the database for the given sql query, there doesn't exist a ResultSet.next() (i.e. that method returns false after the first call) so your while loop body is never entered; you should display your notification in that case.

    kind regards,

    Jos
    The only person who got everything done by Friday was Robinson Crusoe.

  8. #8
    juhiswt is offline Member
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    @JosAH thanx alot ...

  9. #9
    RichersooN is offline Senior Member
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    I think your problem is quite similar to my problem:

    http://www.java-forums.org/database/...return-same-i-
    need-refresh.html

    There is bug on resultset

  10. #10
    JosAH's Avatar
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    Quote Originally Posted by RichersooN View Post
    I think your problem is quite similar to my problem:

    http://www.java-forums.org/database/...return-same-i-
    need-refresh.html

    There is bug on resultset
    Have you read this thread? What the OP described most certainly wasn't a bug on the ResultSet part. b.t.w. the bugbase is full of bugs that aren't bugs ...

    kind regards,

    Jos
    The only person who got everything done by Friday was Robinson Crusoe.

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