I want to look for something that matches a enum: Divisions:U6,U7,U8...
It works when i do this.
public ArrayList<Training> zoekTrainingen(Ploegen p) throws
ApplicationException {
ArrayList<Training> tr = new ArrayList<>();
Connection conn = ConnectionManager.getConnection(driver,
dburl, login, paswoord);
try (PreparedStatement stmt = conn.prepareStatement(
"select * from trainingen");) {
stmt.execute();
ResultSet r = stmt.getResultSet();
while (r.next()) {
---
}
} catch (SQLException sqlEx) {
throw new ApplicationException("");
}
finally {
return tr;
}
}
}
but when I do this:
try (PreparedStatement stmt = conn.prepareStatement(
"select * from trainingen where Divsion = ?");) {
stmt.setString(1, p.getDivision());
I get nothing
The code is attempting to set a String parameter using an Enum. It should get the String value of the Enum and pass to the setString method.
try (PreparedStatement stmt = conn.prepareStatement(
"select * from trainingen where Divsion = ?");) {
stmt.setString(1, p.getDivision().toString());
Related
This question already has answers here:
What is a NullPointerException, and how do I fix it?
(12 answers)
Closed 10 months ago.
public List<Order> getAllOrdersByCustomerId(int customerId) throws SQLException {
List<Order> AllOrdersByCustomerId = new ArrayList<>();
Connection con = null;
PreparedStatement pstmt = null;
ResultSet rs = null;
try {
String sqlQuery = "SELECT * FROM dbo.Orders WHERE customer_id = ?";
con = JDBCConnection.getConnection();
pstmt = con.prepareStatement(sqlQuery);
pstmt.setInt(1, customerId);
pstmt.executeUpdate();
} catch (Exception e) {
e.printStackTrace();
} finally {
if (con != null) {
JDBCConnection.closeConnection(con);
}
if (rs != null) {
JDBCConnection.closeResultSet(rs);
}
}
return AllOrdersByCustomerId;
}
//Exception in thread "main" java.lang.NullPointerException: Cannot invoke "java.util.List.iterator()" because "lo" is null
You should use ResultSet to read your Order of SQL query, and add the Order into your List, like below:
public List<Order> getAllOrdersByCustomerId(int customerId) throws SQLException {
List<Order> allOrdersByCustomerId = new ArrayList<>();
String sqlQuery = "SELECT * FROM dbo.Orders WHERE customer_id = ?";
try (Connection con = JDBCConnection.getConnection();
PreparedStatement pstmt = con.prepareStatement(sqlQuery)) {
pstmt.setInt(1, customerId);
try (ResultSet rs = pstmt.executeQuery()) {
while (rs.next()) {
Order order = new Order();
String id = rs.getString("ORDER_ID");
order.setId(id);
// get and set your values ...
allOrdersByCustomerId.add(order);
}
}
} catch (Exception e) {
e.printStackTrace();
}
return allOrdersByCustomerId;
}
I have a login servlet where I have a login query in my post method from the query I am getting username, password, company name and ID
I am storing all this values in a variable like
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String companyDB,nameDB,idDB;
try {
con = DBConnection.createConnection();
statement = con.createStatement();
String sql = " SELECT MT_USERS.MT_USERS_VCLOGINCODE AS USERID, MT_USERS.MT_USERS_VCUSERPASSWORD AS PASSWORDID, MT_USERS.MT_USERS_VCUSERNAME AS NAME, (SELECT MT_DISTRIBUTR_VCDISTRIBUTRNAME FROM MT_DISTRIBUTR WHERE MT_DISTRIBUTR_VCDISTRIBUTRCODE = MT_USERS.MT_DISTRIBUTR_VCDISTRIBUTRCODE) AS COMPANYNAME ,(SELECT mt_distributr_vcdistributrcode FROM mt_distributr WHERE MT_DISTRIBUTR_VCDISTRIBUTRCODE = MT_USERS.MT_DISTRIBUTR_VCDISTRIBUTRCODE) AS ID FROM MT_USERS WHERE MT_USERS_VCLOGINCODE='admin' AND MT_USERS_VCUSERPASSWORD ='admin'";
resultSet = statement.executeQuery(sql);
if (resultSet.next()) {
companyDB = resultSet.getString("COMPANYNAME");
nameDB = resultSet.getString("name");
idDB = resultset.getString("ID");
}
} catch (SQLException e) {
e.printStackTrace();
}
}
Now I have an another class where I am writing a query and in that query I want to use idDB like
My new class is
public class Outlet {
Connection con = null;
Statement statement = null;
ResultSet resultSet = null;
public List<String> getoutlet() throws ClassNotFoundException, SQLException {
List<String> list = new ArrayList<String>();
con = DBConnection.createConnection();
statement = con.createStatement();
try {
ResultSet resultSet = statement.executeQuery("select * from ecustomer where CUSTOMERIDENTIFIER in(select CUSTOMERIDENTIFIER from mt_distributrol where mt_distributr_vcdistributrcode = 'AAAA'");
while (resultSet.next()) {
list.add(resultSet.getString("CUSTOMERDESCRIPTOR"));
}
} catch (SQLException e) {
e.printStackTrace();
}
return list;
}
}
Where mt_distributr_vcdistributrcode = 'AAAA'" at the place of 'AAAA' I have to pass a variable which has the value of idDB
You may use a prepared statement here:
String sql = "SELECT CUSTOMERDESCRIPTOR FROM ecustomer WHERE CUSTOMERIDENTIFIER IN (";
sql += "SELECT CUSTOMERIDENTIFIER FROM mt_distributrol ";
sql += "WHERE mt_distributr_vcdistributrcode = ?)");
PreparedStatement ps = con.prepareStatement(sql);
ps.setString(1, "AAAA");
ResultSet rs = ps.executeQuery();
while (rs.next()) {
list.add(resultSet.getString("CUSTOMERDESCRIPTOR"));
}
I actually find that MkYong does a good job of explaining prepared statements in Java, see here, but any good documentation is a good place to start looking. And see Oracle Tutorial.
I have a requirement to create separate POJO which will set/get sql ResultSet and use its methods throughout my project code like below. I have created below 2 classes
public class Tester3
{
public MyResultSet test() throws SQLException{
MyResultSet mrs = new MyResultSet();
PreparedStatement ps = null;
String values = null;
boolean flag = false;
String one = "'12'";
String two = "'jt'";
String a = null;
String b = null;
try {
if(flag==true)
{
values = "'3%'";
a =null;
b = "OR id IN(\'" +a+ "\')";
}else
{
values = "'%'";
a = one + "," + two;
b = "AND id IN("+a+")";
}
String sql = "SELECT * FROM veracodetable where orts like PARAM RAMAN";
sql = sql.replaceFirst("PARAM", values);
sql = sql.replaceFirst("RAMAN", b);
System.out.println("SQL: "+sql);
ps = new Connection1().getConnection().prepareStatement(sql);
ps.executeQuery();
mrs.setRs(ps.executeQuery());
System.out.println("ResultSet: "+mrs.getRs().next());
} catch (SQLException e) {
e.printStackTrace();
}
return mrs;
}
public static void main(String[] args) throws SQLException {
Tester3 t = new Tester3();
MyResultSet rs = t.test();
System.out.println("ResultSet: "+rs.getRs().next());
}
}
public class MyResultSet {
ResultSet rs = null;
public ResultSet getRs() {
return rs;
}
public void setRs(ResultSet rs) {
this.rs = rs;
}
}
When executed above code with separate POJO MyResultSet, I don't get any result in ResultSet. However if I skip POJO implementation and use resultSet directly, I am able to get results.
Is rs.getRs() invoking at all? If not, why?
I would separate the statements as they dont't perform the same function, and then populate;
PreparedStatemet ps = null;
ResultSet rs = null;
if(flag){
String stmt = "...?...?";
ps = con.preparedStatement(stmt);
ps.setString(0,a);
ps.setString(1,b);
rs = ps.executeQuery;
}else{
String stmt = "...?...?";
ps = con.preparedStatement(stmt);
ps.setString(0,a);
ps.setString(1,b);
rs = ps.executeQuery;
}
}
I tried to select some data from a MYSQL database tab and insert them into another MYSQL database table.
This is my servlet code
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
processRequest(request, response);
PrintWriter out = response.getWriter();
String name = request.getParameter("name");
ArrayList al = null;
int size = 0;
size = AcceptDao.getData(name);
if (size>0) {
out.println("<script type=\"text/javascript\">");
out.println("alert('Successfully Employee Added');");
out.println("</script>");
} else {
out.println("<script type=\"text/javascript\">");
out.println("alert('Try Again');");
out.println("</script>");
}
}
and here is my java code to do select and insert data.
public static int getData(String Uname) {
ArrayList al = null;
int status = 0;
String name = null;
String role = null;
String pass = null;
try {
Connection con = ConnectionProvider.getCon();
String query = "SELECT noty_name,noty_user_role,noty_pass FROM notification WHERE noty_name='" + Uname + "'";
Statement st = con.createStatement();
ResultSet rs = st.executeQuery(query);
al = new ArrayList();
while (rs.next()) {
name = rs.getString("noty_name");
role = rs.getString("noty_user_role");
pass = rs.getString("noty_pass");
}
PreparedStatement ps = con.prepareStatement("INSERT INTO employee (name,user_role,pass) values(?,?,?)");
ps.setString(1, name);
ps.setString(2, role);
ps.setString(3, pass);
status = ps.executeUpdate();
} catch (Exception e) {
}
return status;
}
this isn't work properly. this code doesn't do select and insert. What is the wrong with this code.
Please note that the code part for "insert" is outside the loop. So only the last data in the loop will be inserted, if available.
Moreover there is no need of while(rs.next) loop. you can use if(rs.next) condition if you are sure that you be passing a unique name in the request.
while (rs.next()) {
name = rs.getString("noty_name");
role = rs.getString("noty_user_role");
pass = rs.getString("noty_pass");
}
/* The Below part is wrong */
PreparedStatement ps = con.prepareStatement("INSERT INTO employee (name,user_role,pass) values(?,?,?)");
ps.setString(1, name);
ps.setString(2, role);
ps.setString(3, pass);
status = ps.executeUpdate();
Instead use this below code
public static int getData(String Uname) {
ArrayList al = null;
int status = 0;
String name = null;
String role = null;
String pass = null;
try {
Connection con = ConnectionProvider.getCon();
String query = "SELECT noty_name,noty_user_role,noty_pass FROM notification WHERE name='" + Uname + "'";
Statement st = con.createStatement();
ResultSet rs = st.executeQuery(query);
al = new ArrayList();
PreparedStatement ps = con.prepareStatement("INSERT INTO employee (name,user_role,pass) values(?,?,?)");
while (rs.next()) {
name = rs.getString("noty_name");
role = rs.getString("noty_user_role");
pass = rs.getString("noty_pass");
ps.setString(1, name);
ps.setString(2, role);
ps.setString(3, pass);
status = ps.executeUpdate();
}
} catch (Exception e) {
}
return status;
}
Please help me fix the error in this program. The problem is, even if I use the correct username and password, I can't create a verified login.
public class LoginDao {
public static boolean CheckUser(String Username,String Password)
{
boolean st =false;
String dbUsername, dbPassword;
try{
Class.forName("com.mysql.jdbc.Driver");
Connection con=DBConnection.getConnection();
String qry ="select *user where Username=? and Password=?";
PreparedStatement pst = con.prepareStatement(qry);
//pst.setString(1, Username);
//pst.setString(2, Password);
pst.executeQuery(qry);
ResultSet rs = pst.getResultSet();
while(rs.next()){
dbUsername = rs.getString("Username");
dbPassword = rs.getString("Password");
if(dbUsername.equals(Username) && dbPassword.equals(Password)){
System.out.println("Welcome");
st = true;
}
}
}
catch(Exception e)
{
e.printStackTrace();
}
return st;
}
}
Check your SQL query? You are missing a FROM before * and user. Also you need to set the parameters when using a PreparedStatement, you have them commented out.
UPDATE
Try this:
public class LoginDao {
public static boolean CheckUser(final String username, final String password) {
final String qry ="SELECT * FROM user WHERE Username=? AND Password=?";
Connection con = null;
PreparedStatement pst;
ResultSet rs = null;
try {
Class.forName("com.mysql.jdbc.Driver");
con = DBConnection.getConnection();
pst = con.prepareStatement(qry);
pst.setString(1, username);
pst.setString(2, password);
pst.executeQuery(qry);
rs = pst.getResultSet();
// Notice I changed the 'while' by 'if'
if (rs.next()) {
return (username.equals(rs.getString("Username")) && password.equals(rs.getString("Password")));
}
} catch (final Exception e) {
e.printStackTrace();
} finally {
// close/release (database resources) 'con', 'pst', 'rs' here
}
return false;
}
}