fetching data from the database

[saswati_mishra]

Alerts

<%
Connection conn = null;
ResultSet rs1 = null;
Statement stmt = null;
ResultSetMetaData rsmd = null;
String query="select * from alertdata";

try {
Class c = Class.forName("org.postgresql.driver");
conn = DriverManager.getConnection("jdbc:postgresql://192.168.128.150:5432/thirdeye", "postgres", "postgres");
stmt = conn.createStatement();
rs1 = stmt.executeQuery(query);

int columns=0;
rsmd = rs1.getMetaData();
columns = rsmd.getColumnCount();
}
catch (SQLException e) {
System.out.println("Error occurred " + e);
}
%>

<% // for the header cells
try {
for (int i=1; i<=columns; i++) {
out.write("" + rsmd.getColumnLabel(i) + "");
}
%>

<% // for each row in the database table
while (rs1.next()) {
out.write("");
for (int i=1; i<=columns; i++) {
out.write("" + rs1.getString(i) + "");
}
out.write("");
}

// close the connection and the statement
stmt.close();
conn.close();
}
catch (SQLException e) {
System.out.println("Error " + e);
}

finally {
try {
if (stmt != null)
stmt.close();
} catch (SQLException e) {}
try {
if (conn != null)
conn.close();
} catch (SQLException e) {}
}

%>

[Ezzaral]

You have defined 'columns' locally inside a try-catch block and are attempting to use it in another block. Move the declaration outside the first block so that it is visible to the second.

[saswati_mishra]

You have defined 'columns' locally inside a try-catch block and are attempting to use it in another block. Move the declaration outside the first block so that it is visible to the second.

My code is working now. Thanks a lot for your help.

Saswati

[peter_budo]

You aware that accessing any database with JSP is not recommended and should be avoid. Servlets been design for this task...

[saswati_mishra]

Hi,

I am very new in java/jsp. Could you please explain me how to use servlets instead of jsp.

Thanks a lot in advance.

Saswati

[peter_budo]

Story of a Servlet
Basic Servlet Structure also there is more ont that site
Introduction to Servlets

And there many-many more you just need to specify what exactly you are looking for

[~s.o.s~]

Also you should consider using JSTL instead of embedding business logic / scriptlets inside your JSP file.

Read the following:
http://java.sun.com/products/jsp/jstl/
http://www.developer.com/java/ejb/article.php/1447551