Category: java Mysql

Java & MySQL – SavePoint ”; Previous Next The new JDBC 3.0 Savepoint interface gives you the additional transactional control. Most modern DBMS, support savepoints within their environments such as Oracle”s PL/SQL. When you set a savepoint you define a logical rollback point within a transaction. If an error occurs past a savepoint, you can use the rollback method to undo either all the changes or only the changes made after the savepoint. The Connection object has two new methods that help you manage savepoints − setSavepoint(String savepointName) − Defines a new savepoint. It also returns a Savepoint object. releaseSavepoint(Savepoint savepointName) − Deletes a savepoint. Notice that it requires a Savepoint object as a parameter. This object is usually a savepoint generated by the setSavepoint() method. There is one rollback (String savepointName) method, which rolls back work to the specified savepoint. The following example illustrates the use of a Savepoint object − try{ //Assume a valid connection object conn conn.setAutoCommit(false); Statement stmt = conn.createStatement(); //set a Savepoint Savepoint savepoint1 = conn.setSavepoint(“Savepoint1”); String SQL = “INSERT INTO Employees ” + “VALUES (106, 20, ”Rita”, ”Tez”)”; stmt.executeUpdate(SQL); //Submit a malformed SQL statement that breaks String SQL = “INSERTED IN Employees ” + “VALUES (107, 22, ”Sita”, ”Tez”)”; stmt.executeUpdate(SQL); // If there is no error, commit the changes. conn.commit(); }catch(SQLException se){ // If there is any error. conn.rollback(savepoint1); } In this case, none of the above INSERT statement would success and everything would be rolled back. Following is the example, which makes use of setSavepoint and rollback described. This sample code has been written based on the environment and database setup done in the previous chapters. Copy and paste the following example in TestApplication.java, compile and run as follows − import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Savepoint; import java.sql.Statement; public class TestApplication { static final String DB_URL = “jdbc:mysql://localhost/TUTORIALSPOINT”; static final String USER = “guest”; static final String PASS = “guest123”; static final String QUERY = “SELECT id, first, last, age FROM Employees”; static final String DELETE_QUERY = “DELETE FROM Employees WHERE ID = 8”; static final String DELETE_QUERY_1 = “DELETE FROM Employees WHERE ID = 9”; public static void printResultSet(ResultSet rs) throws SQLException{ // Ensure we start with first row rs.beforeFirst(); while(rs.next()){ // Display values System.out.print(“ID: ” + rs.getInt(“id”)); System.out.print(“, Age: ” + rs.getInt(“age”)); System.out.print(“, First: ” + rs.getString(“first”)); System.out.println(“, Last: ” + rs.getString(“last”)); } System.out.println(); } public static void main(String[] args) { // Open a connection try(Connection conn = DriverManager.getConnection(DB_URL, USER, PASS); Statement stmt = conn.createStatement( ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE); ) { conn.setAutoCommit(false); ResultSet rs = stmt.executeQuery(QUERY); System.out.println(“List result set for reference….”); printResultSet(rs); // delete row having ID = 8 // But save point before doing so. Savepoint savepoint1 = conn.setSavepoint(“ROWS_DELETED_1”); System.out.println(“Deleting row….”); stmt.executeUpdate(DELETE_QUERY); // Rollback the changes after save point 1. conn.rollback(savepoint1); // delete rows having ID = 9 // But save point before doing so. conn.setSavepoint(“ROWS_DELETED_2”); System.out.println(“Deleting row….”); stmt.executeUpdate(DELETE_QUERY_1); rs = stmt.executeQuery(QUERY); System.out.println(“List result set for reference….”); printResultSet(rs); // Clean-up environment rs.close(); } catch (SQLException e) { e.printStackTrace(); } } } Now, let us compile the above example as follows − C:>javac TestApplication.java C:> When you run TestApplication, it produces the following result − C:>java TestApplication List result set for reference…. ID: 1, Age: 23, First: Zara, Last: Ali ID: 2, Age: 30, First: Mahnaz, Last: Fatma ID: 3, Age: 35, First: Zaid, Last: Khan ID: 4, Age: 33, First: Sumit, Last: Mittal ID: 5, Age: 40, First: John, Last: Paul ID: 7, Age: 20, First: Sita, Last: Singh ID: 8, Age: 20, First: Rita, Last: Tez ID: 9, Age: 20, First: Sita, Last: Singh Deleting row…. Deleting row…. List result set for reference…. ID: 1, Age: 23, First: Zara, Last: Ali ID: 2, Age: 30, First: Mahnaz, Last: Fatma ID: 3, Age: 35, First: Zaid, Last: Khan ID: 4, Age: 33, First: Sumit, Last: Mittal ID: 5, Age: 40, First: John, Last: Paul ID: 7, Age: 20, First: Sita, Last: Singh ID: 8, Age: 20, First: Rita, Last: Tez C:> Print Page Previous Next Advertisements ”;

Java & MySQL – Drop Database Example ”; Previous Next This chapter provides an example on how to drop an existing Database using JDBC application. Before executing the following example, make sure you have the following in place − To execute the following example you need to replace the username and password with your actual user name and password. Your MySQL is up and running. NOTE − This is a serious operation and you have to make a firm decision before proceeding to delete a database because everything you have in your database would be lost. Required Steps The following steps are required to create a new Database using JDBC application − Import the packages − Requires that you include the packages containing the JDBC classes needed for database programming. Most often, using import java.sql.* will suffice. Open a connection − Requires using the DriverManager.getConnection() method to create a Connection object, which represents a physical connection with a database server. Deleting a database does not require database name to be in your database URL. Following example would delete STUDENTS database. Execute a query − Requires using an object of type Statement for building and submitting an SQL statement to delete the database. Clean up the environment − try with resources automatically closes the resources. Sample Code Copy and paste the following example in TestApplication.java, compile and run as follows − import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; import java.sql.Statement; public class TestApplication { static final String DB_URL = “jdbc:mysql://localhost/”; static final String USER = “guest”; static final String PASS = “guest123”; public static void main(String[] args) { // Open a connection try(Connection conn = DriverManager.getConnection(DB_URL, USER, PASS); Statement stmt = conn.createStatement(); ) { String sql = “DROP DATABASE STUDENTS”; stmt.executeUpdate(sql); System.out.println(“Database dropped successfully…”); } catch (SQLException e) { e.printStackTrace(); } } } Now let us compile the above example as follows − C:>javac TestApplication.java C:> When you run TestApplication, it produces the following result − C:>java TestApplication Database dropped successfully… C:> Print Page Previous Next Advertisements ”;

Java & MySQL – CallableStatement ”; Previous Next The CallableStatement interface is used to execute a call to a database stored procedure. Suppose, you need to execute the following stored procedure in TUTORIALSPOINT database − DELIMITER $$ DROP PROCEDURE IF EXISTS `TUTORIALSPOINT`.`getEmpName` $$ CREATE PROCEDURE `TUTORIALSPOINT`.`getEmpName` (IN EMP_ID INT, OUT EMP_FIRST VARCHAR(255)) BEGIN SELECT first INTO EMP_FIRST FROM Employees WHERE ID = EMP_ID; END $$ DELIMITER ; Three types of parameters exist: IN, OUT, and INOUT. The PreparedStatement object only uses the IN parameter. The CallableStatement object can use all the three. Here are the definitions of each − Parameter Description IN A parameter whose value is unknown when the SQL statement is created. You bind values to IN parameters with the setXXX() methods. OUT A parameter whose value is supplied by the SQL statement it returns. You retrieve values from theOUT parameters with the getXXX() methods. INOUT A parameter that provides both input and output values. You bind variables with the setXXX() methods and retrieve values with the getXXX() methods. The following code snippet shows how to employ the Connection.prepareCall() method to instantiate a CallableStatement object based on the preceding stored procedure − CallableStatement cstmt = null; try { String SQL = “{call getEmpName (?, ?)}”; cstmt = conn.prepareCall (SQL); . . . } catch (SQLException e) { . . . } finally { . . . } The String variable SQL, represents the stored procedure, with parameter placeholders. Using the CallableStatement objects is much like using the PreparedStatement objects. You must bind values to all the parameters before executing the statement, or you will receive an SQLException. If you have IN parameters, just follow the same rules and techniques that apply to a PreparedStatement object; use the setXXX() method that corresponds to the Java data type you are binding. When you use OUT and INOUT parameters you must employ an additional CallableStatement method, registerOutParameter(). The registerOutParameter() method binds the JDBC data type, to the data type that the stored procedure is expected to return. Once you call your stored procedure, you retrieve the value from the OUT parameter with the appropriate getXXX() method. This method casts the retrieved value of SQL type to a Java data type. Closing CallableStatement Object Just as you close other Statement object, for the same reason you should also close the CallableStatement object. A simple call to the close() method will do the job. If you close the Connection object first, it will close the CallableStatement object as well. However, you should always explicitly close the CallableStatement object to ensure proper cleanup. CallableStatement cstmt = null; try { String SQL = “{call getEmpName (?, ?)}”; cstmt = conn.prepareCall (SQL); . . . } catch (SQLException e) { . . . } finally { cstmt.close(); } We”re using try with resources which handles the resource closure automatically. Following example demonstrates all of the above said concepts. This code has been written based on the environment and database setup done in the previous chapter. Copy and paste the following example in TestApplication.java, compile and run as follows − import java.sql.CallableStatement; import java.sql.Connection; import java.sql.DriverManager; import java.sql.SQLException; public class TestApplication { static final String DB_URL = “jdbc:mysql://localhost/TUTORIALSPOINT”; static final String USER = “guest”; static final String PASS = “guest123”; static final String QUERY = “{call getEmpName (?, ?)}”; public static void main(String[] args) { // Open a connection try(Connection conn = DriverManager.getConnection(DB_URL, USER, PASS); CallableStatement stmt = conn.prepareCall(QUERY); ) { // Bind values into the parameters. stmt.setInt(1, 102); // This would set ID // Because second parameter is OUT so register it stmt.registerOutParameter(2, java.sql.Types.VARCHAR); //Use execute method to run stored procedure. System.out.println(“Executing stored procedure…” ); stmt.execute(); //Retrieve employee name with getXXX method String empName = stmt.getString(2); System.out.println(“Emp Name with ID: 102 is ” + empName); } catch (SQLException e) { e.printStackTrace(); } } } Now let us compile the above example as follows − C:>javac TestApplication.java C:> When you run TestApplication, it produces the following result − C:>java TestApplication Executing stored procedure… Emp Name with ID: 102 is Zaid C:> JDBC SQL Escape Syntax The escape syntax gives you the flexibility to use database specific features unavailable to you by using standard JDBC methods and properties. The general SQL escape syntax format is as follows − {keyword ”parameters”} Here are the following escape sequences, which you would find very useful while performing the JDBC programming − d, t, ts Keywords They help identify date, time, and timestamp literals. As you know, no two DBMSs represent time and date the same way. This escape syntax tells the driver to render the date or time in the target database”s format. For Example − {d ”yyyy-mm-dd”} Where yyyy = year, mm = month; dd = date. Using this syntax {d ”2009-09-03”} is March 9, 2009. Here is a simple example showing how to INSERT date in a table − //Create a Statement object stmt = conn.createStatement(); //Insert data ==> ID, First Name, Last Name, DOB String sql=”INSERT INTO STUDENTS VALUES” + “(100,”Zara”,”Ali”, {d ”2001-12-16”})”; stmt.executeUpdate(sql); Similarly, you can use one of the following two syntaxes, either t or ts − {t ”hh:mm:ss”} Where hh = hour; mm = minute; ss = second. Using this syntax {t ”13:30:29”} is 1:30:29 PM. {ts ”yyyy-mm-dd hh:mm:ss”} This is combined syntax of the above two syntax for ”d” and ”t” to represent timestamp. escape Keyword This keyword identifies the escape character used in LIKE clauses. Useful when using the SQL wildcard %, which matches zero or more characters.

Java & MySQL – Updating a ResultSet ”; Previous Next The ResultSet interface contains a collection of update methods for updating the data of a result set. As with the get methods, there are two update methods for each data type − One that takes in a column name. One that takes in a column index. For example, to update a String column of the current row of a result set, you would use one of the following updateString() methods − S.N. Methods & Description 1 public void updateString(int columnIndex, String s) throws SQLException Changes the String in the specified column to the value of s. 2 public void updateString(String columnName, String s) throws SQLException Similar to the previous method, except that the column is specified by its name instead of its index. There are update methods for the eight primitive data types, as well as String, Object, URL, and the SQL data types in the java.sql package. Updating a row in the result set changes the columns of the current row in the ResultSet object, but not in the underlying database. To update your changes to the row in the database, you need to invoke one of the following methods. S.N. Methods & Description 1 public void updateRow() Updates the current row by updating the corresponding row in the database. 2 public void deleteRow() Deletes the current row from the database 3 public void refreshRow() Refreshes the data in the result set to reflect any recent changes in the database. 4 public void cancelRowUpdates() Cancels any updates made on the current row. 5 public void insertRow() Inserts a row into the database. This method can only be invoked when the cursor is pointing to the insert row. Following is the example, which makes use of the ResultSet.CONCUR_UPDATABLE and ResultSet.TYPE_SCROLL_INSENSITIVE described in the Result Set tutorial. This example would explain INSERT, UPDATE and DELETE operation on a table. It should be noted that tables you are working on should have Primary Key set properly. Let”s update our referece table first. Drop the table and Create the table Employees again as follows − mysql> use TUTORIALSPOINT; mysql> drop table Employees; Query OK, 0 rows affected (0.08 sec) mysql> create table Employees -> ( -> id int primary key auto_increment, -> age int not null, -> first varchar (255), -> last varchar (255) -> ); Query OK, 0 rows affected (0.08 sec) mysql> Create Data Records Finally you create few records in Employee table as follows − mysql> INSERT INTO Employees(AGE, FIRST, LAST) VALUES (18, ”Zara”, ”Ali”); Query OK, 1 row affected (0.05 sec) mysql> INSERT INTO Employees(AGE, FIRST, LAST) VALUES (25, ”Mahnaz”, ”Fatma”); Query OK, 1 row affected (0.00 sec) mysql> INSERT INTO Employees(AGE, FIRST, LAST) VALUES (30, ”Zaid”, ”Khan”); Query OK, 1 row affected (0.00 sec) mysql> INSERT INTO Employees(AGE, FIRST, LAST) VALUES (28, ”Sumit”, ”Mittal”); Query OK, 1 row affected (0.00 sec) mysql> Copy and paste the following example in TestApplication.java, compile and run as follows − import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; public class TestApplication { static final String DB_URL = “jdbc:mysql://localhost/TUTORIALSPOINT”; static final String USER = “guest”; static final String PASS = “guest123”; static final String QUERY = “SELECT id, first, last, age FROM Employees”; public static void printResultSet(ResultSet rs) throws SQLException{ // Ensure we start with first row rs.beforeFirst(); while(rs.next()){ // Display values System.out.print(“ID: ” + rs.getInt(“id”)); System.out.print(“, Age: ” + rs.getInt(“age”)); System.out.print(“, First: ” + rs.getString(“first”)); System.out.println(“, Last: ” + rs.getString(“last”)); } System.out.println(); } public static void main(String[] args) { // Open a connection try(Connection conn = DriverManager.getConnection(DB_URL, USER, PASS); Statement stmt = conn.createStatement( ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE); ResultSet rs = stmt.executeQuery(QUERY); ) { System.out.println(“List result set for reference….”); printResultSet(rs); // Loop through result set and add 5 in age // Move to Before first position so while-loop works properly rs.beforeFirst(); //STEP 7: Extract data from result set while(rs.next()){ // Retrieve by column name int newAge = rs.getInt(“age”) + 5; rs.updateDouble( “age”, newAge ); rs.updateRow(); } System.out.println(“List result set showing new ages…”); printResultSet(rs); // Insert a record into the table. // Move to insert row and add column data with updateXXX() System.out.println(“Inserting a new record…”); rs.moveToInsertRow(); rs.updateString(“first”,”John”); rs.updateString(“last”,”Paul”); rs.updateInt(“age”,40); // Commit row rs.insertRow(); System.out.println(“List result set showing new set…”); printResultSet(rs); } catch (SQLException e) { e.printStackTrace(); } } } Now let us compile the above example as follows − C:>javac TestApplication.java C:> When you run TestApplication, it produces the following result − C:>java TestApplication List result set for reference…. ID: 1, Age: 18, First: Zara, Last: Ali ID: 2, Age: 25, First: Mahnaz, Last: Fatma ID: 3, Age: 30, First: Zaid, Last: Khan ID: 4, Age: 28, First: Sumit, Last: Mittal List result set showing new ages… ID: 1, Age: 23, First: Zara, Last: Ali ID: 2, Age: 30, First: Mahnaz, Last: Fatma ID: 3, Age: 35, First: Zaid, Last: Khan ID: 4, Age: 33, First: Sumit, Last: Mittal Inserting a new record… List result set showing new set… ID: 1, Age: 23, First: Zara, Last: Ali ID: 2, Age: 30, First: Mahnaz, Last: Fatma ID: 3, Age: 35, First: Zaid, Last: Khan ID: 4, Age: 33, First: Sumit, Last: Mittal ID: 5, Age: 40, First: John, Last: Paul C:> Print Page Previous Next Advertisements ”;

Java & MySQL – Commit & Rollback ”; Previous Next Once you are done with your changes and you want to commit the changes then call commit() method on connection object as follows − conn.commit( ); Otherwise, to roll back updates to the database made using the Connection named conn, use the following code − conn.rollback( ); The following example illustrates the use of a commit and rollback object − try{ //Assume a valid connection object conn conn.setAutoCommit(false); Statement stmt = conn.createStatement(); String SQL = “INSERT INTO Employees ” + “VALUES (106, 20, ”Rita”, ”Tez”)”; stmt.executeUpdate(SQL); //Submit a malformed SQL statement that breaks String SQL = “INSERTED IN Employees ” + “VALUES (107, 22, ”Sita”, ”Singh”)”; stmt.executeUpdate(SQL); // If there is no error. conn.commit(); }catch(SQLException se){ // If there is any error. conn.rollback(); } In this case, none of the above INSERT statement would success and everything would be rolled back. Following is the example, which makes use of commit and rollback described. This sample code has been written based on the environment and database setup done in the previous chapters. Copy and paste the following example in TestApplication.java, compile and run as follows − import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; public class TestApplication { static final String DB_URL = “jdbc:mysql://localhost/TUTORIALSPOINT”; static final String USER = “guest”; static final String PASS = “guest123”; static final String QUERY = “SELECT id, first, last, age FROM Employees”; static final String INSERT_QUERY = “INSERT INTO Employees (first, last, age) values(”Rita”, ”Tez”, 20)”; static final String INSERT_QUERY_2 = “INSERT INTO Employees (first, last, age) values(”Sita”, ”Singh”, 20)”; public static void printResultSet(ResultSet rs) throws SQLException{ // Ensure we start with first row rs.beforeFirst(); while(rs.next()){ // Display values System.out.print(“ID: ” + rs.getInt(“id”)); System.out.print(“, Age: ” + rs.getInt(“age”)); System.out.print(“, First: ” + rs.getString(“first”)); System.out.println(“, Last: ” + rs.getString(“last”)); } System.out.println(); } public static void main(String[] args) { Connection conn = null; Statement stmt = null; try{ // Open a connection System.out.println(“Connecting to database…”); conn = DriverManager.getConnection(DB_URL,USER,PASS); // Set auto commit as false. conn.setAutoCommit(false); // Execute a query to create statment with // required arguments for RS example. System.out.println(“Creating statement…”); stmt = conn.createStatement( ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE); // INSERT a row into Employees table System.out.println(“Inserting one row….”); stmt.executeUpdate(INSERT_QUERY); // INSERT one more row into Employees table stmt.executeUpdate(INSERT_QUERY_2); // Commit data here. System.out.println(“Commiting data here….”); conn.commit(); // Now list all the available records. String sql = “SELECT id, first, last, age FROM Employees”; ResultSet rs = stmt.executeQuery(sql); System.out.println(“List result set for reference….”); printResultSet(rs); // Clean-up environment rs.close(); stmt.close(); conn.close(); }catch(SQLException se){ se.printStackTrace(); // If there is an error then rollback the changes. System.out.println(“Rolling back data here….”); try{ if(conn!=null) conn.rollback(); }catch(SQLException se2){ se2.printStackTrace(); } }catch(Exception e){ e.printStackTrace(); }finally{ // finally block used to close resources try{ if(stmt!=null) stmt.close(); }catch(SQLException se2){ se2.printStackTrace(); } try{ if(conn!=null) conn.close(); }catch(SQLException se){ se.printStackTrace(); } } } } Now let us compile the above example as follows − C:>javac TestApplication.java C:> When you run TestApplication, it produces the following result − C:>java TestApplication Connecting to database… Creating statement… Inserting one row…. Commiting data here…. List result set for reference…. ID: 1, Age: 23, First: Zara, Last: Ali ID: 2, Age: 30, First: Mahnaz, Last: Fatma ID: 3, Age: 35, First: Zaid, Last: Khan ID: 4, Age: 33, First: Sumit, Last: Mittal ID: 5, Age: 40, First: John, Last: Paul ID: 6, Age: 20, First: Rita, Last: Tez ID: 7, Age: 20, First: Sita, Last: Singh C:> Print Page Previous Next Advertisements ”;

Java & MySQL – Statement ”; Previous Next JDBC Statement interface defines the methods and properties to enable send SQL commands to MySQL database and retrieve data from the database. Statement is used for general-purpose access to your database. It is useful when you are using static SQL statements at runtime. The Statement interface cannot accept parameters. Before you can use a Statement object to execute a SQL statement, you need to create one using the Connection object”s createStatement( ) method, as in the following example − Statement stmt = null; try { stmt = conn.createStatement( ); . . . } catch (SQLException e) { . . . } finally { . . . } Once you”ve created a Statement object, you can then use it to execute an SQL statement with one of its three execute methods. boolean execute (String SQL) − Returns a boolean value of true if a ResultSet object can be retrieved; otherwise, it returns false. Use this method to execute SQL DDL statements or when you need to use truly dynamic SQL. int executeUpdate (String SQL) − Returns the number of rows affected by the execution of the SQL statement. Use this method to execute SQL statements for which you expect to get a number of rows affected – for example, an INSERT, UPDATE, or DELETE statement. ResultSet executeQuery (String SQL) − Returns a ResultSet object. Use this method when you expect to get a result set, as you would with a SELECT statement. Closing Statement Object Just as you close a Connection object to save database resources, for the same reason you should also close the Statement object. A simple call to the close() method will do the job. If you close the Connection object first, it will close the Statement object as well. However, you should always explicitly close the Statement object to ensure proper cleanup. Statement stmt = null; try { stmt = conn.createStatement( ); . . . } catch (SQLException e) { . . . } finally { stmt.close(); } We”re using try with resources which handles the resource closure automatically. Following example demonstrates all of the above said concepts. This code has been written based on the environment and database setup done in the previous chapter. Copy and paste the following example in TestApplication.java, compile and run as follows − import java.sql.Connection; import java.sql.DriverManager; import java.sql.ResultSet; import java.sql.SQLException; import java.sql.Statement; public class TestApplication { static final String DB_URL = “jdbc:mysql://localhost/TUTORIALSPOINT”; static final String USER = “guest”; static final String PASS = “guest123”; static final String QUERY = “SELECT id, first, last, age FROM Employees”; static final String UPDATE_QUERY = “UPDATE Employees set age=30 WHERE id=103”; public static void main(String[] args) { // Open a connection try(Connection conn = DriverManager.getConnection(DB_URL, USER, PASS); Statement stmt = conn.createStatement(); ) { // Let us check if it returns a true Result Set or not. Boolean ret = stmt.execute(UPDATE_QUERY); System.out.println(“Return value is : ” + ret.toString() ); // Let us update age of the record with ID = 103; int rows = stmt.executeUpdate(UPDATE_QUERY); System.out.println(“Rows impacted : ” + rows ); // Let us select all the records and display them. ResultSet rs = stmt.executeQuery(QUERY); // Extract data from result set while (rs.next()) { // Retrieve by column name System.out.print(“ID: ” + rs.getInt(“id”)); System.out.print(“, Age: ” + rs.getInt(“age”)); System.out.print(“, First: ” + rs.getString(“first”)); System.out.println(“, Last: ” + rs.getString(“last”)); } rs.close(); } catch (SQLException e) { e.printStackTrace(); } } } Now let us compile the above example as follows − C:>javac TestApplication.java C:> When you run TestApplication, it produces the following result − C:>java TestApplication Return value is : false Rows impacted : 1 ID: 100, Age: 18, First: Zara, Last: Ali ID: 101, Age: 25, First: Mehnaz, Last: Fatma ID: 102, Age: 30, First: Zaid, Last: Khan ID: 103, Age: 30, First: Sumit, Last: Mittal C:> Print Page Previous Next Advertisements ”;

Java & MySQL – PreparedStatement ”; Previous Next The PreparedStatement interface extends the Statement interface, which gives you added functionality with a couple of advantages over a generic Statement object. This statement gives you the flexibility of supplying arguments dynamically. Creating PreparedStatement Object PreparedStatement pstmt = null; try { String SQL = “Update Employees SET age = ? WHERE id = ?”; pstmt = conn.prepareStatement(SQL); . . . } catch (SQLException e) { . . . } finally { . . . } All parameters in JDBC are represented by the ? symbol, which is known as the parameter marker. You must supply values for every parameter before executing the SQL statement. The setXXX() methods bind values to the parameters, where XXX represents the Java data type of the value you wish to bind to the input parameter. If you forget to supply the values, you will receive an SQLException. Each parameter marker is referred by its ordinal position. The first marker represents position 1, the next position 2, and so forth. This method differs from that of Java array indices, which starts at 0. All of the Statement object”s methods for interacting with the database (a) execute(), (b) executeQuery(), and (c) executeUpdate() also work with the PreparedStatement object. However, the methods are modified to use SQL statements that can input the parameters. Closing PreparedStatement Object Just as you close a Statement object, for the same reason you should also close the PreparedStatement object. A simple call to the close() method will do the job. If you close the Connection object first, it will close the PreparedStatement object as well. However, you should always explicitly close the PreparedStatement object to ensure proper cleanup. PreparedStatement pstmt = null; try { String SQL = “Update Employees SET age = ? WHERE id = ?”; pstmt = conn.prepareStatement(SQL); . . . } catch (SQLException e) { . . . } finally { pstmt.close(); } We”re using try with resources which handles the resource closure automatically. Following example demonstrates all of the above said concepts. This code has been written based on the environment and database setup done in the previous chapter. Copy and paste the following example in TestApplication.java, compile and run as follows − import java.sql.Connection; import java.sql.DriverManager; import java.sql.PreparedStatement; import java.sql.ResultSet; import java.sql.SQLException; public class TestApplication { static final String DB_URL = “jdbc:mysql://localhost/TUTORIALSPOINT”; static final String USER = “guest”; static final String PASS = “guest123”; static final String QUERY = “SELECT id, first, last, age FROM Employees”; static final String UPDATE_QUERY = “UPDATE Employees set age=? WHERE id=?”; public static void main(String[] args) { // Open a connection try(Connection conn = DriverManager.getConnection(DB_URL, USER, PASS); PreparedStatement stmt = conn.prepareStatement(UPDATE_QUERY); ) { // Bind values into the parameters. stmt.setInt(1, 35); // This would set age stmt.setInt(2, 102); // This would set ID // Let us update age of the record with ID = 102; int rows = stmt.executeUpdate(); System.out.println(“Rows impacted : ” + rows ); // Let us select all the records and display them. ResultSet rs = stmt.executeQuery(QUERY); // Extract data from result set while (rs.next()) { // Retrieve by column name System.out.print(“ID: ” + rs.getInt(“id”)); System.out.print(“, Age: ” + rs.getInt(“age”)); System.out.print(“, First: ” + rs.getString(“first”)); System.out.println(“, Last: ” + rs.getString(“last”)); } rs.close(); } catch (SQLException e) { e.printStackTrace(); } } } Now let us compile the above example as follows − C:>javac TestApplication.java C:> When you run TestApplication, it produces the following result − C:>java TestApplication Return value is : false Rows impacted : 1 ID: 100, Age: 18, First: Zara, Last: Ali ID: 101, Age: 25, First: Mehnaz, Last: Fatma ID: 102, Age: 35, First: Zaid, Last: Khan ID: 103, Age: 30, First: Sumit, Last: Mittal C:> Print Page Previous Next Advertisements ”;

Java & MySQL – Environment Setup ”; Previous Next To start developing with JDBC, you should setup your JDBC environment by following the steps shown below. We assume that you are working on a Windows platform. Install Java Java SE is available for download for free. To download click here, please download a version compatible with your operating system. Follow the instructions to download Java, and run the .exe to install Java on your machine. Once you have installed Java on your machine, you would need to set environment variables to point to correct installation directories. Setting Up the Path for Windows 2000/XP Assuming you have installed Java in c:Program Filesjavajdk directory − Right-click on ”My Computer” and select ”Properties”. Click on the ”Environment variables” button under the ”Advanced” tab. Now, edit the ”Path” variable and add the path to the Java executable directory at the end of it. For example, if the path is currently set to C:WindowsSystem32, then edit it the following way C:WindowsSystem32;c:Program Filesjavajdkbin Setting Up the Path for Windows 95/98/ME Assuming you have installed Java in c:Program Filesjavajdk directory − Edit the ”C:autoexec.bat” file and add the following line at the end − SET PATH = %PATH%;C:Program Filesjavajdkbin Setting Up the Path for Linux, UNIX, Solaris, FreeBSD Environment variable PATH should be set to point to where the Java binaries have been installed. Refer to your shell documentation if you have trouble doing this. For example, if you use bash as your shell, then you would add the following line at the end of your .bashrc − export PATH = /path/to/java:$PATH” You automatically get both JDBC packages java.sql and javax.sql, when you install J2SE Development Kit. Install MySQL Database The most important thing you will need, of course is an actual running database with a table that you can query and modify. MySQL DB − MySQL is an open source database. You can download it from MySQL Official Site. We recommend downloading the full Windows installation. In addition, download and install MySQL Administrator as well as MySQL Query Browser. These are GUI based tools that will make your development much easier. Finally, download and unzip MySQL Connector/J (the MySQL JDBC driver) in a convenient directory. For the purpose of this tutorial we will assume that you have installed the driver at C:Program FilesMySQLmysql-connector-java-5.1.8. Accordingly, set CLASSPATH variable to C:Program FilesMySQLmysql-connector-java-5.1.8mysql-connector-java-5.1.8-bin.jar. Your driver version may vary based on your installation. Set Database Credential When we install MySQL database, its administrator ID is set to root and it gives provision to set a password of your choice. Using root ID and password you can either create another user ID and password, or you can use root ID and password for your JDBC application. There are various database operations like database creation and deletion, which would need administrator ID and password. For rest of the JDBC tutorial, we would use MySQL Database with guest as ID and guest123 as password. If you do not have sufficient privilege to create new users, then you can ask your Database Administrator (DBA) to create a user ID and password for you. Create Database To create the TUTORIALSPOINT database, use the following steps − Step 1 Open a Command Prompt and change to the installation directory as follows − C:> C:>cd Program FilesMySQLbin C:Program FilesMySQLbin> Note − The path to mysqld.exe may vary depending on the install location of MySQL on your system. You can also check documentation on how to start and stop your database server. Step 2 Start the database server by executing the following command, if it is already not running. C:Program FilesMySQLbin>mysqld C:Program FilesMySQLbin> Step 3 Create the TUTORIALSPOINT database by executing the following command − C:Program FilesMySQLbin> mysqladmin create TUTORIALSPOINT -u guest -p Enter password: ******** C:Program FilesMySQLbin> Create Table To create the Employees table in TUTORIALSPOINT database, use the following steps − Step 1 Open a Command Prompt and change to the installation directory as follows − C:> C:>cd Program FilesMySQLbin C:Program FilesMySQLbin> Step 2 Login to the database as follows − C:Program FilesMySQLbin>mysql -u guest -p Enter password: ******** mysql> Step 3 Create the table Employees as follows − mysql> use TUTORIALSPOINT; mysql> create table Employees -> ( -> id int not null, -> age int not null, -> first varchar (255), -> last varchar (255) -> ); Query OK, 0 rows affected (0.08 sec) mysql> Create Data Records Finally you create few records in Employee table as follows − mysql> INSERT INTO Employees VALUES (100, 18, ”Zara”, ”Ali”); Query OK, 1 row affected (0.05 sec) mysql> INSERT INTO Employees VALUES (101, 25, ”Mahnaz”, ”Fatma”); Query OK, 1 row affected (0.00 sec) mysql> INSERT INTO Employees VALUES (102, 30, ”Zaid”, ”Khan”); Query OK, 1 row affected (0.00 sec) mysql> INSERT INTO Employees VALUES (103, 28, ”Sumit”, ”Mittal”); Query OK, 1 row affected (0.00 sec) mysql> For a complete understanding on MySQL database, study the MySQL Tutorial. Now you are ready to start experimenting with JDBC. Next chapter gives you a sample example on JDBC Programming. Print Page Previous Next Advertisements ”;

Java & MySQL – Useful Resources ”; Previous Next The following resources contain additional information on Java & MySQL. Please use them to get more in-depth knowledge on this topic. Useful Links on Java & MySQL Sun”s Site on JDBC − Sun Developer Network giving link on JDBC material. MySQL Connector/J − MySQL Connector/J is the official JDBC driver for MySQL. The JavaTM Tutorials − The Java Tutorials are practical guides for programmers who want to use the Java programming language to create applications. JavaTM 2 SDK, Standard Edition − Official site for JavaTM 2 SDK, Standard Edition Free Java Download − Download Java for your desktop computer now! Sun Developer Network − Sun Microsystem”s official website listing down all the API documentation, latest Java Technologies, Books and other resource. Useful Books on Java & MySQL To enlist your site on this page, please drop an email to [email protected] Print Page Previous Next Advertisements ”;

Java & MySQL – Quick Guide ”; Previous Next Java & MySQL – Overview JDBC stands for Java Database Connectivity, which is a standard Java API for database-independent connectivity between the Java programming language and a wide range of databases. The JDBC library includes APIs for each of the tasks mentioned below that are commonly associated with database usage. Making a connection to a database. Creating SQL or MySQL statements. Executing SQL or MySQL queries in the database. Viewing & Modifying the resulting records. Fundamentally, JDBC is a specification that provides a complete set of interfaces that allows for portable access to an underlying database. Java can be used to write different types of executables, such as − Java Applications Java Applets Java Servlets Java ServerPages (JSPs) Enterprise JavaBeans (EJBs). All of these different executables are able to use a JDBC driver to access a database, and take advantage of the stored data. JDBC provides the same capabilities as ODBC, allowing Java programs to contain database-independent code. Pre-Requisite Before moving further, you need to have a good understanding of the following two subjects − Core JAVA Programming SQL or MySQL Database JDBC Architecture The JDBC API supports both two-tier and three-tier processing models for database access but in general, JDBC Architecture consists of two layers − JDBC API − This provides the application-to-JDBC Manager connection. JDBC Driver API − This supports the JDBC Manager-to-Driver Connection. The JDBC API uses a driver manager and database-specific drivers to provide transparent connectivity to heterogeneous databases. The JDBC driver manager ensures that the correct driver is used to access each data source. The driver manager is capable of supporting multiple concurrent drivers connected to multiple heterogeneous databases. Following is the architectural diagram, which shows the location of the driver manager with respect to the JDBC drivers and the Java application − Common JDBC Components The JDBC API provides the following interfaces and classes − DriverManager − This class manages a list of database drivers. Matches connection requests from the java application with the proper database driver using communication sub protocol. The first driver that recognizes a certain subprotocol under JDBC will be used to establish a database Connection. Driver − This interface handles the communications with the database server. You will interact directly with Driver objects very rarely. Instead, you use DriverManager objects, which manages objects of this type. It also abstracts the details associated with working with Driver objects. Connection − This interface with all methods for contacting a database. The connection object represents communication context, i.e., all communication with database is through connection object only. Statement − You use objects created from this interface to submit the SQL statements to the database. Some derived interfaces accept parameters in addition to executing stored procedures. ResultSet − These objects hold data retrieved from a database after you execute an SQL query using Statement objects. It acts as an iterator to allow you to move through its data. SQLException − This class handles any errors that occur in a database application. The JDBC 4.0 Packages The java.sql and javax.sql are the primary packages for JDBC 4.0. This is the latest JDBC version at the time of writing this tutorial. It offers the main classes for interacting with your data sources. The new features in these packages include changes in the following areas − Automatic database driver loading. Exception handling improvements. Enhanced BLOB/CLOB functionality. Connection and statement interface enhancements. National character set support. SQL ROWID access. SQL 2003 XML data type support. Annotations. Java & MySQL – Environment Setup To start developing with JDBC, you should setup your JDBC environment by following the steps shown below. We assume that you are working on a Windows platform. Install Java Java SE is available for download for free. To download click here, please download a version compatible with your operating system. Follow the instructions to download Java, and run the .exe to install Java on your machine. Once you have installed Java on your machine, you would need to set environment variables to point to correct installation directories. Setting Up the Path for Windows 2000/XP Assuming you have installed Java in c:Program Filesjavajdk directory − Right-click on ”My Computer” and select ”Properties”. Click on the ”Environment variables” button under the ”Advanced” tab. Now, edit the ”Path” variable and add the path to the Java executable directory at the end of it. For example, if the path is currently set to C:WindowsSystem32, then edit it the following way C:WindowsSystem32;c:Program Filesjavajdkbin Setting Up the Path for Windows 95/98/ME Assuming you have installed Java in c:Program Filesjavajdk directory − Edit the ”C:autoexec.bat” file and add the following line at the end − SET PATH = %PATH%;C:Program Filesjavajdkbin Setting Up the Path for Linux, UNIX, Solaris, FreeBSD Environment variable PATH should be set to point to where the Java binaries have been installed. Refer to your shell documentation if you have trouble doing this. For example, if you use bash as your shell, then you would add the following line at the end of your .bashrc − export PATH = /path/to/java:$PATH” You automatically get both JDBC packages java.sql and javax.sql, when you install J2SE Development Kit. Install Database The most important thing you will need, of course is an actual running database with a table that you can query and modify. Install a database that is most suitable for you. You can have plenty of choices and most