Develop Reference

Looking for the optimization of the below code

I have found below code buggy as it degrades the performance of extjs3 grid, i am looking for possibilities of optimization at query or code level, as per my analysis, if we extract out the query there are two nested inner queries which are responding slow, in addition, the code inside while loop trying to find the unique id, can't we have distinct in query, or joins rather than inner queries.
Please suggest me the best practice to follow in order to achieve optimization.
public boolean isSCACreditOverviewGridVisible(String sessionId) {
Connection conn = null;
ResultSet rs = null;
PreparedStatement ps = null;
boolean result = false;
try {
CommonUtility commUtil = new CommonUtility();
List<String> hmIds = new ArrayList<String>();
Map<String, String> tmStockMap = new TreeMap<String, String>();
Set<String> setRecentCertificate = new HashSet<String>();
String managerAccountId = sessionInfo.getMembershipAccount();
String stockQuery = " select memberId , RootCertficateId from stockposition sp where sp.stocktype = 'TR' and sp.memberId "
+ " IN ( select hm2.accountId from "
DATALINK
+ ".holdingmembers hm2 "
+ " where hm2.holdingId = ( select holdingId from "
DATALINK
+ ".holdingmembers hm1 where hm1.accountId = ? )) "
+ " order by sp.createdDate desc ";
conn = getChildDBConnection();
if (null != conn) {
ps = conn.prepareStatement(stockQuery);
ps.setString(1, managerAccountId);
rs = ps.executeQuery();
if (null != rs) {
while (rs.next()) {
String memberId = rs.getString("memberId");
String rootCertficateId = rs
.getString("RootCertficateId");
if (tmStockMap.containsKey(rootCertficateId)) {
continue;
}
hmIds.add(memberId);
tmStockMap.put(rootCertficateId, memberId);
}
}
rs.close();
ps.close();
if (null != hmIds && !hmIds.isEmpty()) {
String inIds = commUtil.getInStateParam(hmIds);
String mostRecentLicense = "Select RootCertificateId , memberaccountid from "
+ OctopusSchema.octopusSchema
+ ".certificate c where c.memberaccountid IN ("
+ inIds
+ ") and c.isrootcertificate=0 and c.certificationstatusid > 1 order by c.modifieddate desc";
ps = conn.prepareStatement(mostRecentLicense);
rs = ps.executeQuery();
if (null != rs) {
while (rs.next()) {
String rootCertficateId = rs
.getString("RootCertificateId");
String memberaccountid = rs
.getString("memberaccountid");
if (setRecentCertificate.contains(memberaccountid)) {
continue;
}
setRecentCertificate.add(memberaccountid);
if (tmStockMap.containsKey(rootCertficateId)) {
result = true;
break;
}
}
}
rs.close();
ps.close();
} else {
result = false;
}
}
} catch (Exception e) {
LOGGER.error(e);
} finally {
closeDBReferences(conn, ps, null, rs);
}
return result;
}
QUERY:
select RootCertficateId,memberId from stockposition sp where sp.stocktype = 'TR' and sp.memberId
IN ( select hm2.accountId from
DATALINK.holdingmembers hm2
where hm2.holdingId = ( select holdingId from
DATALINK.holdingmembers hm1 where hm1.accountId = '4937' ))
order by sp.createdDate DESC;

One quick approach would be a substition of your IN by EXISTS. If your inner queryes return a lot of rows, it would be a lot more efficient. It depends if your subquery returns a lot of results.
SQL Server IN vs. EXISTS Performance

What should we have to pass to method to complete it

What should I need to pass to complete this method. The error is :
The method fireSelect(String, String[], String[]) in the type DBConnection is not applicable for the arguments (String).
This is the method :
public static ResultSet fireSelect(String query, String[] types,
String[] values) {
try {
PreparedStatement ps = getInstance().prepareStatement(query);
if (types != null) {
for (int i = 0; i < types.length; i++) {
if (types[i].equals("int"))
ps.setInt((i + 1), Integer.parseInt(values[i]));
else if (types[i].equals("string"))
ps.setString((i + 1), values[i]);
else if (types[i].equals("double"))
ps.setDouble((i + 1), Double.parseDouble(values[i]));
}
}
return ps.executeQuery();
} catch (Exception e) {
try {
connection = null;
if (cnt < 2) {
connection = getInstance();
cnt++;
fireSelect(query, types, values);
} else {
cnt = 0;
}
} catch (Exception ee) {
System.out.println("Exception :" + ee);
}
}
return null;
}
and this is I have use to pass during cal this method
ResultSet rs = DBConnection.fireSelect(
"select dealer_id,car_servicing,car_servicing,cost,features "
+ " from dealer_car,carservicing where "
+ "dealer_car.car_servicing=carservicing.car_servicing and dealer_id="
+ dealerId);

As your SQL doesn't expect any paramaters, you can simply do
ResultSet rs = DBConnection.fireSelect(sql, null, null);

It expects 3 arguments, and you provided only one.
Just call like,
ResultSet rs = DBConnection.fireSelect("Select Query", null, null);

You're missing String[] types and String[] values, you could pass it as null (in your case), should be better if you call it like follow:
String sql = "select dealer_id,car_servicing,car_servicing,cost,features from
dealer_car,carservicing where dealer_car.car_servicing=carservicing.car_servicing
and dealer_id=:dealer_id";
String[] types = new String[]{"int"}; //or maybe string?
String[] vals = new String[]{dealerId};
ResultSet rs = DBConnection.fireSelect(sql, types, vals);

you need to pass all 3 argumens to the function fireSelect()

Your SQL does'nt expect a paramter, it is build up by concatenation, what is not good. fireSelect seems to be e helper to use a prepared statement and you are avoiding this.
fireSelect("select * from ... where id=?", new String[]{"int"}, new String[]{"42"});
even this
fireSelect((String)null,(String[])null,(String[])null);

Your fireSelect method is expecting 3 arguments:
You can use something like:
ResultSet rs = DBConnection.fireSelect(
"select dealer_id,car_servicing,car_servicing,cost,features "
+ " from dealer_car,carservicing where "
+ " dealer_car.car_servicing=carservicing.car_servicing and dealer_id="
+ dealerId,
new String[]{"int"},
new String[]{dealerId});

How to make one mySQL's table column invisible

I am running a query on ID column but I don't want it to be visible in my frame/pane. How can I achieve this? Shall I make another table, is there a function in sql/mysql which allows to hide columns? I tried to google it but havent found anything yet.
Here is the code:
public void tableChanged(TableModelEvent e) {
int row = e.getFirstRow();
int col = e.getColumn();
model = (MyTableModel) e.getSource();
String stulpPav = model.getColumnName(col);
Object data = model.getValueAt(row, col);
Object studId = model.getValueAt(row, 0);
System.out.println("tableChanded works");
try {
new ImportData(stulpPav, data, studId);
} catch (ClassNotFoundException e1) {
e1.printStackTrace();
} catch (SQLException e1) {
e1.printStackTrace();
}
}
public class ImportData {
Connection connection = TableWithBottomLine.getConnection();
public ImportData(String a, Object b, Object c)
throws ClassNotFoundException, SQLException {
Statement stmt = null;
try {
String stulpPav = a;
String duom = b.toString();
String studId = c.toString();
System.out.println(duom);
connection.setAutoCommit(false);
stmt = connection.createStatement();
stmt.addBatch("update finance.fin set " + stulpPav + " = " + duom
+ " where ID = " + studId + ";");
stmt.executeBatch();
connection.commit();
} catch (BatchUpdateException e) {
e.printStackTrace();
} catch (SQLException e) {
e.printStackTrace();
} finally {
if (stmt != null)
stmt.close();
connection.setAutoCommit(true);
System.out.println("Data was imported to database");
}
}
}
public class MyTableModel extends AbstractTableModel{
int rowCount;
Object data [][];
String columnNames [];
public MyTableModel() throws SQLException{
String query ="SELECT ID, tbl_Date as Date, Flat, Mobile, Food, Alcohol, Transport, Outdoor, Pauls_stuff, Income, Stuff FROM finance.fin";
ResultSet rs ;
Connection connection = TableWithBottomLine.getConnection();
Statement stmt = null;
stmt = connection.createStatement();
rs = stmt.executeQuery(query);
rs.last();
rowCount = rs.getRow();
data = new Object[rowCount][11];
rs = stmt.executeQuery(query);
for (int iEil = 0; iEil < rowCount; iEil++){
rs.next();
data[iEil][0] = rs.getInt("ID");
data[iEil][1] = rs.getDate("Date");
data[iEil][2] = rs.getFloat("Flat");
data[iEil][3] = rs.getFloat("Mobile");
data[iEil][4] = rs.getFloat("Food");
data[iEil][5] = rs.getFloat("Alcohol");
data[iEil][6] = rs.getFloat("Transport");
data[iEil][7] = rs.getFloat("Outdoor");
data[iEil][8] = rs.getFloat("Pauls_stuff");
data[iEil][9] = rs.getFloat("Income");
data[iEil][10] = rs.getFloat("Stuff");
}
String[] columnName = {"ID", "Date","Flat","Mobile"
,"Food","Alcohol","Transport", "Outdoor", "Pauls_stuff", "Income", "Stuff"};
columnNames = columnName;
}

This has solved my problem:
table.removeColumn(table.getColumnModel().getColumn(0));
I placed this in my class contructor. This lets remove the column from the view of the table but column 'ID' is still contained in the TableModel. I found that many people looking for an option to exclude specific column (like autoincrement) from SELECT statement in sql / mysql but the language itself doesn't have that feature. So I hope this solution will help others as well.

Don't put ID in the select part of the query
String query ="SELECT tbl_Date as Date, Flat, Mobile, Food, Alcohol, Transport,
Outdoor, Pauls_stuff, Income, Stuff FROM finance.fin";

How to create a list using PreparedStatement?

I have following codes:
-------class------------
private class SystemHealthAlert implements Work {
List<MonitorAlertInstance> systemHealthAlertList;
private String queryString;
// private java.util.Date startDate;
// private java.util.Date endDate;
#Override
public void execute(Connection connection) throws SQLException {
PreparedStatement ps = connection.prepareStatement(queryString);
int index = 1;
ResultSet rs = ps.executeQuery();
int columnCount = rs.getMetaData().getColumnCount();
while(rs.next())
{
//String[] row = new String[columnCount];
//results.set(index, element);
//for (int i=0; i <columnCount ; i++)
// {
// row[i] = rs.getString(i + 1);
// }
systemHealthAlertList.add(row);
}
rs.close();
ps.close();
}
}
---------Method-----------
public List<MonitorAlertInstance> getSystemHealthAlert(Long selectedSensorId) {
List<MonitorAlertInstance> systemHealthAlertList;
try {
// Add SELECT with a nested select to get the 1st row
String queryString = "select min(MONITOR_ALERT_INSTANCE_ID) as MONITOR_ALERT_INSTANCE_ID, description" +
" from ems.monitor_alert_instance " +
" where description in (select description from monitor_alert_instance" +
" where co_mod_asset_id = " + selectedSensorId +
" )" +
" group by description";
SystemHealthAlert work = new SystemHealthAlert();
// work.coModAssetId = coModAssetId;
work.queryString = queryString;
getSession().doWork(work);
systemHealthAlertList = work.systemHealthAlertList;
} catch (RuntimeException re) {
// log.error("getMostRecentObservationId() failed", re);
throw re;
}
//log.info("End");
return systemHealthAlertList;
}
My query returns three rows from DB. How can I return systemHealthAlertList from the class that will have all the three rows of the query.

In method execute, you should fill your List<MonitorAlertInstance> systemHealthAlertList with instances of MonitorAlertInstance. Create a new instance of MonitorAlertInstance inside the while loop where you retrieve the data:
//You don't need this line, remove it
//int columnCount = rs.getMetaData().getColumnCount();
while(rs.next()) {
//create a new instance of MonitorAlertInstance per ResultSet row
MonitorAlertInstance monitor = new MonitorAlertInstance();
//set the fields from the ResultSet in your MonitorAlertInstance fields
//since I don't know the fields of this class, I would use field1 and field2 as examples
monitor.setField1(rs.getInt(1));
monitor.setField2(rs.getString(2));
//and on...
systemHealthAlertList.add(monitor);
}
Apart from this problem, you should initialize your List<MonitorAlertInstance> systemHealthAlertList variable before use it:
systemHealthAlertList = new ArrayList<MonitorAlertInstance>();
while(rs.next()) {
//content from previous code...
}

Define a class/bean to hold the data from one given row. Loop through your rows, and create one instance of that class for each row you have. Add these instances to some List. Return the List of these 3 instances.

Result set returns 3 rows but i am only able to print 2?

The code below gets the information i require from my database but is not printing out all of the information. Firstly i know it is getting all of the correct information from the table because i have tried the query in sql developer.
public static void main(String[] args) {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
try {
conn = getConnection();
String query = "SELECT menu.menu_id, menu_title, dish.dish_id, dish_name, dish_description, dish_price, menu.week_no "
+ "FROM menu, dish, menu_allocation "
+ "WHERE menu.active = '1' "
+ "AND menu.menu_id = menu_allocation.menu_id "
+ "AND dish.dish_id = menu_allocation.dish_id "
+ "AND menu.week_no IN (09, 10, 11)";
stmt = conn.createStatement();
rs = stmt.executeQuery(query);
MenuList list = null;
while (rs.next()) {
list = new MenuList(rs);
System.out.println(rs.getRow());
}
for (int pos = 0; pos < list.size(); pos++) {
Menu menu = list.getMenuAt(pos);
System.out.println(menu.getDescription());
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
rs.close();
stmt.close();
conn.close();
} catch (SQLException e) {
}
}
}
The output from the terminal is as follows:
3 //Number of rows
Fish and Chips //3rd row
Chocolate Cake //2nd row
//Here should be 1st row
BUILD SUCCESSFUL (total time: 2 seconds)
Even though it says there are three rows it has only printed the two. Can anybody see if there is a problem with the above?

It's hard to be sure without seeing the code for the MenuList class but I don't think you need to loop over the ResultSet as MenuList does that for you.
As the MenuList constructor takes the ResultSet in rs as a parameter it probably loops over the ResultSet to create its entries. As you've already called rs.next() in the while of your loop the MenuList misses the first result.
I think you should replace all this:
MenuList list = null;
while (rs.next()) {
list = new MenuList(rs);
System.out.println(rs.getRow());
}
With:
MenuList list = new MenuList(rs);

I would suggest you use a debugger so you understand what your progam is doing.
You appear to be only keeping the last row loaded, so while you have 3 rows, you only keep the last. It appears you are getting two values from the last row.

public static void main(String[] args) {
Connection conn = null;
Statement stmt = null;
ResultSet rs = null;
try {
conn = getConnection();
String query = "SELECT menu.menu_id, menu_title, dish.dish_id, dish_name, dish_description, dish_price, menu.week_no "
+ "FROM menu, dish, menu_allocation "
+ "WHERE menu.active = '1' "
+ "AND menu.menu_id = menu_allocation.menu_id "
+ "AND dish.dish_id = menu_allocation.dish_id "
+ "AND menu.week_no IN (09, 10, 11)";
stmt = conn.createStatement();
rs = stmt.executeQuery(query);
MenuList[3] list = null;
int idx = 0; //Add index
while (rs.next()) {
list[idx] = new MenuList(rs); //use index
idx++; //increment index
System.out.println(rs.getRow());
}
for (int pos = 0; pos < list.size(); pos++) {
Menu menu = list.getMenuAt(pos);//Don't know that
//get menu by index
System.out.println(menu.getDescription());
}
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
rs.close();
stmt.close();
conn.close();
} catch (SQLException e) {
}
}
}