Print fra database

KODEN:

<%

    String driver = "com.mysql.jdbc.Driver";
    String url = "jdbc:mysql://localhost:3306/test";
    String username = "root";
    String password = "";
    Connection connection = null;
    ResultSet rs1 = null;
    ResultSet rs2 = null;
   
    // Establish connection                 
    connection = DriverManager.getConnection(url,username,password);
   
    // Create a statement object
    Statement s = connection.createStatement();
   
    rs1 = s.executeQuery("SELECT * FROM varegrupper ORDER BY navn ASC");
    rs2 = s.executeQuery("SELECT itemname FROM " + rs1.getString("navn") + "");
   
    while (rs1.next() == true)
    {
       
        out.println(rs1.getString("navn"));
       
       
        //while (rs.next()){
        //out.println(rs.getString("itemname") + "<br>");
        //}
    }

    %>

Det lyder som om du ikke faar kaldt rs.next() !

rs1 = s.executeQuery("SELECT * FROM varegrupper ORDER BY navn ASC");
while(rs1.next()) {
    rs2 = s.executeQuery("SELECT itemname FROM " + rs1.getString("navn") + "");
    while(rs2.next()) {
    }
}


vil jeg tro.

Jeg får en "Operation not allowed after ResultSet closed"

på while(rs1.next()) { ...

Hvor kalder du close ?

rs1 = s.executeQuery("SELECT * FROM varegrupper ORDER BY navn ASC");
    while (rs1.next()) {
        rs2 = s.executeQuery("SELECT itemname FROM " + rs1.getString("navn") + "");
        while (rs2.next()) {
        }
    }
    rs1.close();
    rs2.close();
    s.close();

rs1 = s.executeQuery("SELECT * FROM varegrupper ORDER BY navn ASC");
    while (rs1.next()) {
        rs2 = s.executeQuery("SELECT itemname FROM " + rs1.getString("navn") + "");
        while (rs2.next()) {
            // whatever
        }
        rs2.close();
    }
    rs1.close();
    s.close();

boer ikke give den fejl.

Giver samme fejl på linien med while(rs1.next()) { ...

Jeg fatter det ikke :S

<%

    String driver = "com.mysql.jdbc.Driver";
    String url = "jdbc:mysql://localhost:3306/test";
    String username = "eshop";
    String password = "";
    Connection connection = null;
    ResultSet rs1 = null;
    ResultSet rs2 = null;
   
    // Establish connection                 
    connection = DriverManager.getConnection(url,username,password);
   
    // Create a statement object
    Statement s = connection.createStatement();
   
   
    rs1 = s.executeQuery("SELECT * FROM varegrupper ORDER BY navn ASC");
    while (rs1.next()) {
        rs2 = s.executeQuery("SELECT itemname FROM " + rs1.getString("navn") + "");
        while (rs2.next()) {
            // whatever
        }
        rs2.close();
    }
    rs1.close();
    s.close();

    %>

Ah.

Proev lige med 2 connections og 2 statements - en til hver query.

con1 = DriverManager.getConnection(url,username,password);
    s1 = connection.createStatement();
    rs1 = s.executeQuery("SELECT * FROM varegrupper ORDER BY navn ASC");
    while (rs1.next()) {
        con2 = DriverManager.getConnection(url,username,password);
        s2 = connection.createStatement();
        rs2 = s.executeQuery("SELECT itemname FROM " + rs1.getString("navn") + "");
        while (rs2.next()) {
            // whatever
        }
        rs2.close();
        s2.close();
        con2.close();
    }
    rs1.close();
    s1.close();
    con1.close();

JA for faen!
Jeg har ikke rigtig nogen idé om hvorfor der skal 2 forbindelser til, men det virker.
Endelig kode:

<%

    String driver = "com.mysql.jdbc.Driver";
    String url = "jdbc:mysql://localhost:3306/test";
    String username = "eshop";
    String password = "";
    Connection connection = null;
    Connection connection2 = null;
    ResultSet rs1 = null;
    ResultSet rs2 = null;
   
    // Establish connection                 
    connection = DriverManager.getConnection(url,username,password);
    connection2 = DriverManager.getConnection(url,username,password);
   
    // Create a statement object
    Statement s = connection.createStatement();
    Statement s2 = connection2.createStatement();
   
   
    rs1 = s.executeQuery("SELECT * FROM varegrupper ORDER BY navn ASC");
    while (rs1.next()) {
        rs2 = s2.executeQuery("SELECT * FROM " + rs1.getString("navn") + "");
        while (rs2.next()) {
            out.println("Navn: " + rs2.getString("itemname") + "<br>");
            out.println("Pris: " + rs2.getString("price") + "<br>");
            out.println("Info: " + rs2.getString("info") + "<br><br>");
        }
        rs2.close();
    }
    rs1.close();
    s.close();

    %>

TAK!

Det er noedvendigt fordi executeQuery (normalt) ikke henter alle raekker - det er faktisk next kaldet som henter en ny raekke. Og man kan ikke blande resultater fra 2 queries sammen paa en enkelt connection.

Det er et kendt problem. Jeg var vare lidt sloev til at gennemskue det p.g.a. fejlmeddelserne der indikerede noget helt andet.

Og et svar.