Hi,
I'm trying to execute a specific query by clicking a button.I was trying to use inside actionperformed code different Statement and resultSets but every time throws errors.I'll be appreciated if someone give me an example similar to the previous description.
Thanks
Post some code.
What are database operations doing inside an ActionListener? Better to move them to a separate class (preferrably interface based) that you can test without the UI. Then have your ActionListener simply call those methods.
%
//Connection to Database
private void dbConn(){
try {
String mydriver="com.mysql.jdbc.Driver";
String myURL="jdbc:mysql://localhost:3306/packets_db";
String userName = "root";
String password = "";
Class.forName(mydriver);
Connection dbConnection=DriverManager.getConnection(myURL,userName,password);
String MySelectString=" SELECT * FROM `packet` ";
try {
MySelectString=MySelectString.trim();
Statement mystate=dbConnection.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
rs=mystate.executeQuery(MySelectString);
}
catch (SQLException sqle) {
System.out.println("ERROR"+sqle);
}
}
catch (SQLException sqle){
System.out.println("Den yparxei i basi dedomenon!!!!");
} catch (ClassNotFoundException cnfe) {
System.out.println("Den yparxei odriver!!!!!");
}
}
//i'm tying to execute sqlquery
boolean found=false;
try {
dbConn();
while(rs.next()){
Date str=rs.getDate("str_date");
Date end=rs.getDate("end_date");
int IDint=rs.getInt("packet_id");
Date sd=jDateChooser1.getDate();
Date ed=jDateChooser2.getDate();
String sqlquery="SELECT packet_id FROM `packet` WHERE str_date>=sd && end_date<=ed";
rs=mystate.executeQuery(sqlquery);
System.out.println(IDint);
found=true;
}
} catch (SQLException eee) {
System.out.println("ERROR"+eee);
}
if(!found){
jLabel4.setText("***No packet found!!!***");
}
//I'm trying to execute the following Query but throws Statements and //ResultSet errors
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
boolean found=false;
try {
dbConn();
while(rs.next()){
Date str=rs.getDate("str_date");
Date end=rs.getDate("end_date");
int IDint=rs.getInt("packet_id");
Date sd=jDateChooser1.getDate();
Date ed=jDateChooser2.getDate();
String sqlquery="SELECT packet_id FROM `packet` WHERE str_date>=sd && end_date<=ed";
rs=mystate.executeQuery(sqlquery);
System.out.println(IDint);
found=true;
}
} catch (SQLException eee) {
System.out.println("ERROR"+eee);
}
if(!found){
jLabel4.setText("***No packet found!!!***");
}
}
any Help?
Thanks
> //I'm trying to execute the following Query but
> throws Statements and //ResultSet errors
can you post the errors.
Exception in thread "AWT-EventQueue-0" java.lang.NullPointerException
for my ResultSet "rs"
any Help?
try {
MySelectString=MySelectString.trim();
Statement mystate=dbConnection.createStatement(ResultSet.TYPE_SCROLL_SENSITIVE,ResultSet.CONCUR_UPDATABLE);
rs=mystate.executeQuery(MySelectString);
}
catch (SQLException sqle) {
System.out.println("ERROR"+sqle);
}
I do not see where you declared rs as a ResultSet. Try putting in "ResultSet rs = mystate.executeQuery(MySelectString);"
