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How do I turn my INT (id) into a String in my return from MySQL?

I'm trying to my a very simple webapplication, webshop, for cupcakes.
From the webApp you can choose a cupcake form the dropdown with three attributes
(top, bottom, quantity). These are stored in an ArrayList on my sessionScope but all in numbers e.g. Chokolate as 1 and Vanilla as 2. I want to use these topId numbers to ask my DB (MySQL) for what is in 1 and then have it return Chokolate.
I think I am almost there with my code, but can't get it to return my String, as my topId is an Int.
public static Top getTopById(int topId) {
readFromArrayPutInSQL();
String sql = "INSERT INTO cupcaketopping (toppingType, toppingPrice) VALUES (?, ?)";
try {
ConnectionPool connectionPool = new ConnectionPool();
String query = "SELECT toppingType FROM cupcaketopping";
Statement statement = connectionPool.getConnection().createStatement();
ResultSet rs = statement.executeQuery(query);
rs.getString(topId);
} catch (SQLException e) {
throw new RuntimeException(e);
}
return topId; //Here is the problem - I GUESS?
}
Code after changes due to input in comments, seem to be working!
public static Top getTopById(int topId) {
readFromArrayPutInSQL();
String query = "SELECT toppingType FROM cupcaketopping WHERE toppingID = "+topId+"";
try {
ConnectionPool connectionPool = new ConnectionPool();
PreparedStatement preparedStatement = connectionPool.getConnection().prepareStatement(query);
ResultSet rs = preparedStatement.executeQuery(query);
rs.next();
return new Top(rs.getString(1));
//connectionPool.close(); //NOTE! Won't run, IntelliJ is asking me to delete!
} catch (SQLException e) {
throw new RuntimeException(e);
}
}

There are a few problems:
You're selecting all rows from the cupcaketopping table, regardless of the topId. You should probably be using a PreparedStatement, and then use topId as part of your query.
You never call ResultSet#next(). The result set always starts "before" the first row. You have to call next() for each row in the result set (it returns true if there is a row to read).
The ResultSet#getString(int) method gets the String value of the column at the given index of the result. You only select one column, so the argument should probably be 1 (not topId).
You never close the Statement when done with it.
Depending on how your connection pool class works, you might actually need to close the Connection instead.
You never try to use the String returned by rs.getString(topId).
You never try to convert the query result to a Top instance.
Given it's possible the query will return no result, you might want to consider making the return type Optional<Top>.
The sql string seems to have no purpose.
Your code should look more like this:
public Optional<Top> getTopById(int topId) {
Connection conn = ...;
String query = "SELECT toppingType FROM cupcaketopping WHERE id = ?";
// closes the statement via try-with-resources
try (PreparedStatement stat = conn.prepareStatement(query)) {
stat.setInt(1, topId);
ResultSet rs = stat.executeQuery();
// assume unique result (as it's assumed the ID is the primary key)
if (rs.next()) {
// assumes 'Top' has a constructor that takes a 'String'
return Optional.of(new Top(rs.getString(1)));
} else {
return Optional.empty();
}
} catch (SQLException ex) {
throw new RuntimeException(ex);
}
}
Your actual implementation may vary, depending on how the rest of your code is designed.

Refactoring very similar JDBC prepared statements

I am trying to write some basic CRUD operations using JDBC. I'm wondering if there is a way I can use the same prepared statements for multiple tables. Right now, I have a function for every table, and it seems redundant, but I'm unsure how I can make it better.
Some code examples:
public static int insertIntoPeopleFilms(People people) {
int newTableRow = -1;
int peopleid = people.getPeopleid();
for (URL filmUrl : people.getFilms()) {
int filmsid = extractIdFromUrl(filmUrl);
try (Connection conn = createDbConnection()) {
newTableRow = getInsertIntoPeopleFilmsPreparedStatement(peopleid, filmsid, conn).executeUpdate();
} catch (SQLException | ClassNotFoundException e) {
System.out.println(e);
}
}
return newTableRow;
}
public static int insertIntoPeopleSpecies(People people) {
int newTableRow = -1;
int peopleid = people.getPeopleid();
for (URL speciesUrl : people.getSpecies()) {
int speciesid = extractIdFromUrl(speciesUrl);
try (Connection conn = createDbConnection()) {
newTableRow = getInsertIntoPeopleSpeciesPreparedStatement(peopleid, speciesid, conn).executeUpdate();
} catch (SQLException | ClassNotFoundException e) {
System.out.println(e);
}
}
return newTableRow;
}
private static PreparedStatement getInsertIntoPeopleFilmsPreparedStatement(int peopleid, int filmsid, Connection conn) throws SQLException {
PreparedStatement preparedStatement = conn.prepareStatement("INSERT INTO people_films(peopleid, filmsid) VALUES (?,?)");
preparedStatement.setInt(1, peopleid);
preparedStatement.setInt(2, filmsid);
return preparedStatement;
}
private static PreparedStatement getInsertIntoPeopleSpeciesPreparedStatement(int peopleid, int speciesid, Connection conn) throws SQLException {
PreparedStatement preparedStatement = conn.prepareStatement("INSERT INTO people_species(peopleid, speciesid) VALUES (?,?)");
preparedStatement.setInt(1, peopleid);
preparedStatement.setInt(2, speciesid);
return preparedStatement;
}
I essentially have this same code repeated for every table, with the only real difference being the names of the tables. Any advice on reducing the amount of code needed? Am I able to use a table name variable or something similar?

You can't make a single prepared statement that inserts into different tables depending on some parameter.
Identifiers (for instance, table names) must be fixed at the time you prepare the statement. During the prepare, the SQL engine checks your syntax and also checks that the table exists. Once that validation is done, you can use the prepared statement freely and those checks don't need to be done as you execute. If you could change the table name per execution, then the SQL engine would need to re-check every time, which would partially defeat the purpose of preparing the statement.
Once the statement has been prepared, you can only change values. In other words, parameters can be used in place where you would have used a quoted string literal or a numeric literal, but no other part of the query.

Prepared Statement only retrieves the first row

I'm developing a web application in which users can insert a number of "products". These products will be inserted in a MySQL database. I have a problem when I try to retrieve data from a table of my database. Here is my method:
public ArrayList<Product> getProductByAppId(int appId) {
ArrayList<Product> list = new ArrayList<Product>();
String query = "select prodId from app_prod where appId = ?";
try {
preparedStatement = connection.prepareStatement(query);
preparedStatement.setInt(1, appId);
resultSet = preparedStatement.executeQuery();
while (resultSet.next()) {
Product item = getProductById(resultSet.getInt("prodId"));
list.add(item);
}
return list;
} catch (Exception e) {
e.printStackTrace();
}
return null;
}
This method simply gets an int as a parameter and retrieves from the table app_prod all the objects I have stored. The method getProductById it's an helper method and it works properly. When I try to debug my code, I see that I enter in the while cycle only once! So all I see is the very first element in my DB, but I have more than a single product in my DB.
To make things shorter, I've omitted methods to open and close connection because they work properly.
I think the error is something very obvious, but I can't really see it.

OK the problem is the following:
resultSet is declared as a global variable and is being used by both methods.
When the second method changes its contents and gets through it by :
resultSet.next();
And reaches the end of it:
The main outer loop tries to do resultSet.next(), it directly exits from the loop since it had already reached its end beforehand in the getProductById method.

List<Product> list = new ArrayList<>();
try (PreparedStatement preparedStatement = connection.prepareStatement(query)) {
preparedStatement.setInt(1, appId);
try (resultSet = preparedStatement.executeQuery()) {
while (resultSet.next()) {
Product item = getProductById(resultSet.getInt("prodId"));
list.add(item);
}
return list;
}
} catch (Exception e) {
e.printStackTrace();
}
The try-with-resources ensure that statement and resultset are closed (even despite the return).
Also now the variables are local. And that might be the problem: maybe you reused those global fields in getProductById. resultSet would be my guess. (Pardon me.)

Try / Try-with-resources and Connection, Statement and ResultSet closing

I have recently having some discussions with my professor about how to handle the basic jdbc connection scheme. Suppose we want to execute two queries, this is what he proposes
public void doQueries() throws MyException{
Connection con = null;
try {
con = DriverManager.getConnection(dataSource);
PreparedStatement s1 = con.prepareStatement(updateSqlQuery);
PreparedStatement s2 = con.prepareStatement(selectSqlQuery);
// Set the parameters of the PreparedStatements and maybe do other things
s1.executeUpdate();
ResultSet rs = s2.executeQuery();
rs.close();
s2.close();
s1.close();
} catch (SQLException e) {
throw new MyException(e);
} finally {
try {
if (con != null) {
con.close();
}
} catch (SQLException e2) {
// Can't really do anything
}
}
}
I don't like this approach, and I have two questions about it:
1.A) I think that, if any exception is thrown where we do 'other things', or in the line rs.close() or s2.close() then s1 wouldn't have been closed when the method ends. Am I right about that?
1.B) The professor keeps asking me to explicitly close the ResultSet (even when the Statement documentation makes clear that it will close the ResultSet) She says that Sun recommends it. Is there any reason to do so?
Now this is what I think is the correct code for the same thing:
public void doQueries() throws MyException{
Connection con = null;
PreparedStatement s1 = null;
PreparedStatement s2 = null;
try {
con = DriverManager.getConnection(dataSource);
s1 = con.prepareStatement(updateSqlQuery);
s2 = con.prepareStatement(selectSqlQuery);
// Set the parameters of the PreparedStatements and maybe do other things
s1.executeUpdate();
ResultSet rs = s2.executeQuery();
} catch (SQLException e) {
throw new MyException(e);
} finally {
try {
if (s2 != null) {
s2.close();
}
} catch (SQLException e3) {
// Can't do nothing
}
try {
if (s1 != null) {
s1.close();
}
} catch (SQLException e3) {
// Can't do nothing
}
try {
if (con != null) {
con.close();
}
} catch (SQLException e2) {
// Can't do nothing
}
}
}
2.A) Is this code correct? (Is it guaranteed that all will be closed when the method ends?)
2.B) This is very large and verbose (and it gets worse if there are more Statements) Is there any shorter or more elegant way to do this without using try-with-resources?
Finally this is the code I like the most
public void doQueries() throws MyException{
try (Connection con = DriverManager.getConnection(dataSource);
PreparedStatement s1 = con.prepareStatement(updateSqlQuery);
PreparedStatement s2 = con.prepareStatement(selectSqlQuery))
{
// Set the parameters of the PreparedStatements and maybe do other things
s1.executeUpdate();
ResultSet rs = s2.executeQuery();
} catch (SQLException e) {
throw new MyException(e);
}
}
3) Is this code correct? I think my professor doesn't like this way because there is no explicit close of the ResultSet, but she has told me that she is fine with it as long as in the documentation it is clear that all is closed. Can you give any link to the official documentation with a similar example, or based in the documentation show that there is are no problems with this code?

tl;dr
In theory closing the statement closes the result set.
In practice, some faulty JDBC driver implementations failed to do so, notoriously. Thus the advice from your instructor that she learned from the School Of Hard Knocks.
Unless you are familiar with every implementation of every JDBC
driver that might be deployed for your app, use
try-with-resources to auto-close every level of your JDBC
work such as statements and result sets.
Use try-with-resources syntax
None of your code is fully using try-with-resources. In try-with-resources syntax, you declare and instantiate your Connection, PreparedStatement, and ResultSet in parentheses, before the braces. See Tutorial by Oracle.
While your ResultSet is not being explicitly closed in your last code example, it should be closed indirectly when its statement is closed. But as discussed below, it might not be closed because of faulty JDBC driver.
AutoCloseable
Any such objects implementing AutoCloseable will automatically have their close method invoked. So no need for those finally clauses.
How do you know which objects are auto-closable and which are not? Look at their class documentation to see if it declares AutoCloseable as a super-interface. Conversely, see the JavaDoc page for AutoCloseable for a list of all the bundled sub-interfaces and implementing classes (dozens actually).
For example, for SQL work, we see that Connection, Statement, PreparedStatement, ResultSet, and RowSet are all auto-closable but DataSource is not. This makes sense, as DataSource stores data about potential resources (database connections) but is not itself a resource. A DataSource is never “open” so no need to close.
See Oracle Tutorial, The try-with-resources Statement.
Code example
Your last code example is getting close to good, but should have wrapped ResultSet in a try-with-resources statement to get automatically closed.
To quote ResultSet JavaDoc:
A ResultSet object is automatically closed when the Statement object that generated it is closed, re-executed, or used to retrieve the next result from a sequence of multiple results.
As your teacher has been suggesting, there have been serious flaws in some JDBC drivers that failed to live up to the promise of the JDBC spec to close the ResultSet when its Statement or PreparedStatement is closed. So many programmers make a habit of closing each ResultSet object explicitly.
This extra duty is easier now with the try-with-resources syntax. In real work you’ll likely have a try-else around all your AutoCloseable objects such as ResultSet anyways. So my own opinion is: Why not make it a try-with-resources + else? Does not hurt, makes your code more self-documenting about your intentions, and it might help if your code ever encounters one of those faulty JDBC drivers. The only cost is a pair of parens, assuming you’d have a try-catch-else in place anyways.
As stated in the Oracle Tutorial, multiple AutoCloseable objects declared together will be closed in reverse order, just as we would want.
Tip: The try-with-resources syntax allows an optional semicolon on the last declared resource item. I include the semicolon as a habit because it reads well to my eye, is consistent, and facilitates cut-and-paste editing. I include it on your PreparedStatement s2 line.
public void doQueries() throws MyException{
// First try-with-resources.
try ( Connection con = DriverManager.getConnection( dataSource ) ;
PreparedStatement s1 = con.prepareStatement( updateSqlQuery ) ;
PreparedStatement s2 = con.prepareStatement( selectSqlQuery ) ;
) {
… Set parameters of PreparedStatements, etc.
s1.executeUpdate() ;
// Second try-with-resources, nested within first.
try (
ResultSet rs = s2.executeQuery() ;
) {
… process ResultSet
} catch ( SQLException e2 ) {
… handle exception related to ResultSet.
}
} catch ( SQLException e ) {
… handle exception related to Connection or PreparedStatements.
}
}
I suppose there is a more elegant syntax for this kind of work that might be invented in a future programming language. But for now, we have try-with-resources, and I do use it happily. While try-with-resources is not perfectly elegant, it is a big improvement over the older syntax.
By the way, Oracle recommends using a DataSource implementation for getting connections rather than the DriverManager approach seen in your code. Using DataSource throughout your code makes it easier to switch drivers or switch to a connection pool. See if your JDBC driver provides an implementation of DataSource.
Update: Java 9
Now in Java 9 you can initialize the resources before the try-with-resources. See this article. This flexibility may be useful in some scenarios.

The fun thing about JDBC code is that you're coding to a spec where it's not always clear how compliant your implementation is. There are a lot of different databases and drivers and some drivers are better-behaved than others. That tends to make people err on the side of caution, recommending things like closing everything explicitly. You could be ok with closing only the connection here. Closing the resultSet just to be on the safe side is hard to argue with. You don't indicate what database or driver you're using here, i wouldn't want to hardcode in assumptions about the driver that might not be valid for some implementation.
Closing things in sequence does leave you open to problems where an exception can get thrown and cause some of the closes to be skipped. You're right to be concerned about that.
Be aware this is a toy example. Most real code uses a connection pool, where calling the close method doesn't actually close the connection, instead it returns the connection to the pool. So resources may not get closed once you use a pool. If you want to change this code to use a connection pool then you'll have to go back and close the statements at least.
Also if you're objecting to the verbosity of this, the answer to that is to hide the code in reusable utilities that use strategies, resultSet mappers, prepared statement setters, etc. This has all been done before, of course; you'll be on the road to reinventing Spring JDBC.
Speaking of which: Spring JDBC closes everything explicitly (probably because it needs to work with as many drivers as possible, and doesn't want to cause problems due to some driver's not being well-behaved).

This is what I find to be the best solution for handling resources like JDBC. This method provides an immutable function, by leveraging final variables, and only declaring and assigning those variables if they are needed, it is very CPU efficient, and guarantees in all cases, that all resources that are assigned and opened are closed regardless of the state of exceptions. The technique you are using leaves gaps that can result in resource leaks if not carefully implemented to address all scenarios. This technique does not allow for a resource leak provided the pattern is always followed:
1) assign resource
2) try
3) use resource
4) finally close resource
public void doQueries() throws MyException {
try {
final Connection con = DriverManager.getConnection(dataSource);
try {
final PreparedStatement s1 = con.prepareStatement(updateSqlQuery);
try {
// Set the parameters of the PreparedStatements and maybe do other things
s1.executeUpdate();
} finally {
try { s1.close(); } catch (SQLException e) {}
}
final PreparedStatement s2 = con.prepareStatement(selectSqlQuery);
try {
// Set the parameters of the PreparedStatements and maybe do other things
final ResultSet rs = s2.executeQuery();
try {
// Do something with rs
} finally {
try { rs.close(); } catch (SQLException e) {}
}
} finally {
try { s2.close(); } catch (SQLException e) {}
}
} finally {
try { con.close(); } catch (SQLException e) {}
}
} catch (SQLException e) {
throw new MyException(e);
}
}
With Java 7, you can leverage the new try -with-resources to simplify this even more: The new try -with-resources follows the above logic flow, in that it will guarantee all resources include in the with resources block that are assigned get closed. any exception thrown in the with resources block will the thrown, but those assigned resources will still be closed. This code is much simplified and looks like this:
public void doQueries() throws MyException {
try (
final Connection con = DriverManager.getConnection(dataSource);
final PreparedStatement s1 = con.prepareStatement(updateSqlQuery);
final PreparedStatement s2 = con.prepareStatement(selectSqlQuery);
final ResultSet rs = s2.executeQuery()) {
s1.executeUpdate();
// Do something with rs
} catch (SQLException e) {
throw new MyException(e);
}
}
[EDIT]: moved rs assignment into the resources block to show the simplest implementation. In practice, this simple solution does not really work, as this is not efficient. A connection should be reused, since establishing the connection is a very costly operation. Additionally, this simple example does not assign query parameters to the prepared statement. Care should be taken to handle these scenarios, as the the resource block should only include assignment statements. To depict this, I have also added another example
public void doQueries() throws MyException {
final String updateSqlQuery = "select ##servername";
final String selecSqlQuery = "select * from mytable where col1 = ? and col2 > ?";
final Object[] queryParams = {"somevalue", 1};
try (final Connection con = DriverManager.getConnection(dataSource);
final PreparedStatement s1 = newPreparedStatement(con, updateSqlQuery);
final PreparedStatement s2 = newPreparedStatement(con, selectSqlQuery, queryParams);
final ResultSet rs = s2.executeQuery()) {
s1.executeUpdate();
while (!rs.next()) {
// do something with the db record.
}
} catch (SQLException e) {
throw new MyException(e);
}
}
private static PreparedStatement newPreparedStatement(Connection con, String sql, Object... args) throws SQLException
{
final PreparedStatement stmt = con.prepareStatement(sql);
for (int i = 0; i < args.length; i++)
stmt.setObject(i, args[i]);
return stmt;
}

This is indeed the primary motivation for try-with-resources. See the Java tutorials as reference. Your professor is out-of-date. If you want to deal with the result set issue you can always enclose it in another try-with-resources statement.

You could make a util class to handle closing of these resources. i.e
FYI i just ignored SQLExceptions from trying to close resources in the util class, but you could as verywell log or collect and throw them once you are done closing the resources in the collection depending on your needs
public class DBUtil {
public static void closeConnections(Connection ...connections){
if(connections != null ){
for(Connection conn : connections){
if(conn != null){
try {
conn.close();
} catch (SQLException ignored) {
//ignored
}
}
}
}
}
public static void closeResultSets(ResultSet ...resultSets){
if(resultSets != null ){
for(ResultSet rs: resultSets){
if(rs != null){
try {
rs.close();
} catch (SQLException ignored) {
//ignored
}
}
}
}
}
public static void closeStatements(Statement ...statements){
if(statements != null){
for(Statement statement : statements){
if(statement != null){
try {
statement.close();
} catch (SQLException ignored) {
//ignored
}
}
}
}
}
}
and then just call it from you method:
public void doQueries() throws MyException {
Connection con = null;
try {
con = DriverManager.getConnection(dataSource);
PreparedStatement s1 = null;
PreparedStatement s2 = null;
try {
s1 = con.prepareStatement(updateSqlQuery);
s2 = con.prepareStatement(selectSqlQuery);
// Set the parameters of the PreparedStatements and maybe do other things
s1.executeUpdate();
ResultSet rs = null;
try {
rs = s2.executeQuery();
} finally {
DBUtil.closeResultSets(rs);
}
} finally {
DBUtil.closeStatements(s2, s1);
}
} catch (SQLException e) {
throw new MyException(e);
} finally {
DBUtil.closeConnections(con);
}
}

I prefer to let Java auto-close. So I do something like this when I have to set values for ResultSet.
try (Connection conn = DB.getConn();
PreparedStatement ps = conn.prepareStatement("SELECT * FROM x WHERE y = ?")
) {
ps.setString(1, "yValue");
try(ResultSet rs = ps.executeQuery()) {
while(rs.next()) {
...
}
}
} catch (SQLException e) {
e.printStackTrace(e);
...
}

Is it Ok to Pass ResultSet?

In my situation, I am querying a database for a specific return (in this case registration information based on a username).
//Build SQL String and Query Database.
if(formValid){
try {
SQL = "SELECT * FROM users WHERE username=? AND email=?";
Collections.addAll(fields, username, email);
results = services.DataService.getData(SQL, fields);
if (!results.next()){
errMessages.add("User account not found.");
} else {
user = new User();
user.fillUser(results); //Is it ok to pass ResultSet Around?
}
} catch (SQLException e) {
e.printStackTrace();
} finally {
services.DataService.closeDataObjects(); //Does this close the ResultSet I passed to fillUser?
}
}
So once I query the database, if a result is found I create a new User object and populate it with the data I received from the database. I used to do all of this directly in the method that I was pulling the resultset into, but I realized I was doing a lot of redundant coding throughout my project so I moved it all into one central method that lives in the actual User bean.
public void fillUser(ResultSet data) throws SQLException{
setUserId(data.getInt("id"));
setFirstName(data.getString("first_name"));
setLastName(data.getString("last_name"));
setUsername(data.getString("username"));
setType(data.getString("type"));
setEmail(data.getString("email"));
}
I have done a few tests and from what I can determine, because I close the original resultset in the finally block of the query, the resultset that I pass into the fillUser method also gets closed. Or am I wrong and am I seriously leaking data? This is actually the second time I pass a resultset (so its two instances of one) because the block I use to query my database is
public static ResultSet getData(String SQL, ArrayList fields) throws SQLException {
try{
connection = Database.getConnection();
preparedStatement = connection.prepareStatement(SQL);
for(int i=0; i<fields.size(); i++){
Integer num = i + 1;
Object item = fields.get(i);
if(item instanceof String){
preparedStatement.setString(num, (String) item); //Array item is String.
} else if (item instanceof Integer){
preparedStatement.setInt(num, (Integer) item); //Array item is Integer.
}
}
resultSet = preparedStatement.executeQuery();
return resultSet;
}finally{
}
}
All of these code snippets live in separate classes and are reused multiple times throughout my project. Is it ok to pass a resultset around like this, or should I be attempting another method? My goal is to reduce the codes redundancy, but i'm not sure if i'm going about it in a legal manner.

Technically, it's OK to pass result sets, as long as you are not serializing and passing it to a different JVM, and your JDBC connection and statement are still open.
However, it's probably a better software engineer and programming practice to have DB access layer that returns you the result set in a Java encoded way (a list of User in your example). That way, your code would be cleaner and you won't have to worry if the ResultSet is already opened, or you have to scroll it to the top, you name it...

As everyone before me said its a bad idea to pass the result set. If you are using Connection pool library like c3p0 then you can safely user CachedRowSet and its implementation CachedRowSetImpl. Using this you can close the connection. It will only use connection when required. Here is snippet from the java doc:
A CachedRowSet object is a disconnected rowset, which means that it makes use of a connection to its data source only briefly. It connects to its data source while it is reading data to populate itself with rows and again while it is propagating changes back to its underlying data source. The rest of the time, a CachedRowSet object is disconnected, including while its data is being modified. Being disconnected makes a RowSet object much leaner and therefore much easier to pass to another component. For example, a disconnected RowSet object can be serialized and passed over the wire to a thin client such as a personal digital assistant (PDA).
Here is the code snippet for querying and returning ResultSet:
public ResultSet getContent(String queryStr) {
Connection conn = null;
Statement stmt = null;
ResultSet resultSet = null;
CachedRowSetImpl crs = null;
try {
Connection conn = dataSource.getConnection();
stmt = conn.createStatement();
resultSet = stmt.executeQuery(queryStr);
crs = new CachedRowSetImpl();
crs.populate(resultSet);
} catch (SQLException e) {
throw new IllegalStateException("Unable to execute query: " + queryStr, e);
}finally {
try {
if (resultSet != null) {
resultSet.close();
}
if (stmt != null) {
stmt.close();
}
if (conn != null) {
conn.close();
}
} catch (SQLException e) {
LOGGER.error("Ignored", e);
}
}
return crs;
}
Here is the snippet for creating data source using c3p0:
ComboPooledDataSource cpds = new ComboPooledDataSource();
try {
cpds.setDriverClass("<driver class>"); //loads the jdbc driver
} catch (PropertyVetoException e) {
e.printStackTrace();
return;
}
cpds.setJdbcUrl("jdbc:<url>");
cpds.setMinPoolSize(5);
cpds.setAcquireIncrement(5);
cpds.setMaxPoolSize(20);
javax.sql.DataSource dataSource = cpds;