at.chrl.database

Class DB

java.lang.Object

at.chrl.database.DB

public final class DB
extends Object

DB Documentation

This class is used for making SQL query's utilizing the database connection defined in database.properties

Here are the functions that one may use to utilize this class in creating an ease of access to database information.

SELECT (select method)

Parameters:

• Required: String query - Query that will be utilized in select statement.
• Required: ReadStH reader - Interface implementation used to read output ResultSet from select statement.
• Optional: String errMsg - Custom error message that will be logged if query fails.

Returns:(boolean ) Returns true if the query ran successfully.

Purpose:
The select function one to grab data from the database with ease. Utilizing the ReadStT, one may set up query parameters (then use ParamReadStH and set params in setParams()) and read the replied data from the query easily.

Best practices is to create custom classes that implement ReadStT in order to throw the data around.

After the function is called, it automatically closes and recycles the SQL Connection.

Example:

 DB.select("SELECT name FROM test_table WHERE id=?", new ParamReadStH() {
 
        public void setParams(PreparedStatement stmt) throws SQLException {
                stmt.setInt(1, 50);
        }
 
        public void handleRead(ResultSet rset) throws SQLException {
                while (rset.next()) {
                        // Usually here in the custom class you would set it to your needed
                        // var.
                        var = rset.getString("name");
                }
        }
 });
 

INSERT / UPDATE (insertUpdate method)

Parameters:

• Required: String query - Query that will be executed in insert/update statement.
• Required: IUStT batch - Util used to modify query parameters OR add add batches.
• Optional: String errMsg - Custom error message that will be logged if query fails.

Returns:(boolean) Returns true if the query ran successfully.

Purpose:
The insertUpdate function allows one to insert and update database entries. One may utilize it without needing to modify the query at all or provide a IUStH interface implementation to add parameters to statement and/or gather them in batch.

If the IUStH util IS provided in the function's parameters - The coder MUST call the functions stmt.executeBatch() OR stmt.executeUpdate() in order to successfully run the query.
If IUSth util is NOT provided, the query will execute as it is.

Best practices is to create custom classes that implement IUStT in order to modify the query in proficient manners.

After the function is called, it automatically closes and recycles the SQL Connection.

Example:

 DB.insertUpdate("UPDATE test_table SET some_column=1");
 

 DB.insertUpdate("INSERT INTO test_table VALUES (?)", new IUStH() {
 
        public void handleInsertUpdate(PreparedStatement stmt) {
                // Usually this would be data from the custom class that implements
                // IUSth
                String[] batchTestVars = { "bob", "mike", "joe" };
 
                for (String n : batchTestVars) {
                        stmt.setString(1, n);
                        stmt.addBatch();
                }
 
                // REQUIRED
                stmt.executeBatch();
        }
 });
 
 

 DB.insertUpdate("UPDATE test_table SET some_column=? WHERE other_column=?", new IUStH() {
 
        public void handleInsertUpdate(PreparedStatement stmt) {
                stmt.setString(1, "xxx");
                stmt.setInt(2, 10);
                stmt.executeUpdate();
        }
 });
 
 

Author:

Disturbing

Field Summary

Fields

Modifier and Type	Field and Description
protected static org.slf4j.Logger	log Logger

Method Summary

Modifier and Type	Method and Description
static Transaction	beginTransaction() Begins new transaction
static boolean	call(String query, ReadStH reader) Call stored procedure
static boolean	call(String query, ReadStH reader, String errMsg) Call stored procedure
static void	close(PreparedStatement statement) Closes PreparedStatemet, it's connection and last ResultSet
static ResultSet	executeQuerry(PreparedStatement statement) Executes Querry and returns ResultSet
static int	executeUpdate(PreparedStatement statement) Executes PreparedStatement
static void	executeUpdateAndClose(PreparedStatement statement) Executes PreparedStatement and closes it and it's connection
static boolean	insertUpdate(String query) Executes Insert or Update Query not needing any further modification or batching.
static boolean	insertUpdate(String query, IUStH batch) Executes Insert / Update Query.
static boolean	insertUpdate(String query, IUStH batch, String errMsg) Executes Insert or Update Query.
static boolean	insertUpdate(String query, String errMsg) Executes Insert or Update Query not needing any further modification or batching.
static PreparedStatement	prepareStatement(String sql) Creates PreparedStatement with given sql string.
static PreparedStatement	prepareStatement(String sql, int resultSetType, int resultSetConcurrency) Creates PreparedStatement with given sql
static boolean	select(String query, ReadStH reader) Executes Select Query.
static boolean	select(String query, ReadStH reader, String errMsg) Executes Select Query.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

log

protected static final org.slf4j.Logger log

Logger

Method Detail

select

public static boolean select(String query,
                             ReadStH reader)

Executes Select Query. Uses ReadSth to utilize params and return data. Recycles connection after competion.

Parameters:

query -

reader -

Returns:

boolean Success

select

public static boolean select(String query,
                             ReadStH reader,
                             String errMsg)

Executes Select Query. Uses ReadSth to utilize params and return data. Recycles connection after completion.

Parameters:

query -

reader -

errMsg -

Returns:

boolean Success

call

public static boolean call(String query,
                           ReadStH reader)

Call stored procedure

Parameters:

query -

reader -

Returns:

call

public static boolean call(String query,
                           ReadStH reader,
                           String errMsg)

Call stored procedure

Parameters:

query -

reader -

errMsg -

Returns:

insertUpdate

public static boolean insertUpdate(String query)

Executes Insert or Update Query not needing any further modification or batching. Recycles connection after completion.

Parameters:

query -

Returns:

boolean Success

insertUpdate

public static boolean insertUpdate(String query,
                                   String errMsg)

Executes Insert or Update Query not needing any further modification or batching. Recycles connection after completion.

Parameters:

query -

errMsg -

Returns:

success

insertUpdate

public static boolean insertUpdate(String query,
                                   IUStH batch)

Executes Insert / Update Query. Utilizes IUSth for Batching and Query Editing. MUST MANUALLY EXECUTE QUERY / BATACH IN IUSth (No need to close Statement after execution)

Parameters:

query -

batch -

Returns:

boolean Success

insertUpdate

public static boolean insertUpdate(String query,
                                   IUStH batch,
                                   String errMsg)

Executes Insert or Update Query. Utilizes IUSth for Batching and Query Editing. Defines custom error message if error occurs. MUST MANUALLY EXECUTE QUERY / BATACH IN IUSth (No need to Statement after execution) Recycles connection after completion

Parameters:

query -

batch -

errMsg -

Returns:

boolean Success

beginTransaction

public static Transaction beginTransaction()
                                    throws SQLException

Begins new transaction

Returns:

new Transaction object

Throws:

SQLException - if was unable to create transaction

prepareStatement

public static PreparedStatement prepareStatement(String sql)

Creates PreparedStatement with given sql string.
Statemens are created with ResultSet.TYPE_FORWARD_ONLY and ResultSet.CONCUR_READ_ONLY

Parameters:

sql - SQL querry

Returns:

Prepared statement if ok or null if error happend while creating

prepareStatement

public static PreparedStatement prepareStatement(String sql,
                                                 int resultSetType,
                                                 int resultSetConcurrency)

Creates PreparedStatement with given sql

Parameters:

sql - SQL querry

resultSetType - a result set type; one of
ResultSet.TYPE_FORWARD_ONLY,
ResultSet.TYPE_SCROLL_INSENSITIVE, or
ResultSet.TYPE_SCROLL_SENSITIVE

resultSetConcurrency - a concurrency type; one of
ResultSet.CONCUR_READ_ONLY or
ResultSet.CONCUR_UPDATABLE

Returns:

Prepared Statement if ok or null if error happened while creating

executeUpdate

public static int executeUpdate(PreparedStatement statement)

Executes PreparedStatement

Parameters:

statement - PreparedStatement to execute

Returns:

returns result of PreparedStatement.executeQuery() or -1 in case of error

executeUpdateAndClose

public static void executeUpdateAndClose(PreparedStatement statement)

Executes PreparedStatement and closes it and it's connection

Parameters:

statement - PreparedStatement to close

executeQuerry

public static ResultSet executeQuerry(PreparedStatement statement)

Executes Querry and returns ResultSet

Parameters:

statement - preparedStement to execute

Returns:

ResultSet or null if error

close

public static void close(PreparedStatement statement)

Closes PreparedStatemet, it's connection and last ResultSet

Parameters:

statement - statement to close