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Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
Java session17
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Java session17

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  • 1. Java Programming LanguageObjectives In this session, you will learn to: Create applications using the PreparedStatement object Manage database transactions Perform batch updates Create and call stored procedures in JDBC Use metadata in JDBC Ver. 1.0 Session 10 Slide 1 of 43
  • 2. Java Programming LanguageQuerying and Modifying Data Using the PreparedStatement Object The PreparedStatement interface is derived from the Statement interface and is available in the java.sql package. The PreparedStatement object: Allows you to pass runtime parameters to the SQL statements to query and modify the data in a table. Is compiled and prepared only once by JDBC. The future invocation of the PreparedStatement object does not recompile the SQL statements. Helps in reducing the load on the database server and thus improving the performance of the application. Ver. 1.0 Session 10 Slide 2 of 43
  • 3. Java Programming LanguageMethods of the PreparedStatement Interface • The PreparedStatement interface inherits the following methods to execute SQL statements from the Statement interface: – Allows you to pass runtime parameters to the SQL statements to query and modify the data in a table. – int executeUpdate(): Executes an SQL statement, INSERT, UPDATE, or DELETE and returns the count of the rows affected. – boolean execute(): Executes an SQL statement and returns a boolean value. Ver. 1.0 Session 10 Slide 3 of 43
  • 4. Java Programming LanguageMethods of the PreparedStatement Interface (Contd.) • The prepareStatement() method of the Connection object is used to submit parameterized query to a database. • The SQL statement can contain ‘?’ symbol as placeholders that can be replaced by input parameters at runtime. For example: stat=con.prepareStatement("SELECT * FROM authors WHERE au_id = ?"); Ver. 1.0 Session 10 Slide 4 of 43
  • 5. Java Programming LanguageMethods of the PreparedStatement Interface (Contd.) The value of each ‘?’ parameter is set by calling an appropriate setXXX() method, where xxx is the data type of the parameter. For example: stat.setString(1,"1001"); ResultSet result=stat.executeQuery(); Ver. 1.0 Session 10 Slide 5 of 43
  • 6. Java Programming LanguageRetrieving Rows • The code snippet to retrieve books written by an author from the titles table using the PreparedStatement object is: String str = "SELECT * FROM titles WHERE au_id = ?"; PreparedStatement ps= con.prepareStatement(str); ps.setString(1, "1001"); ResultSet rs=ps.executeQuery(); Ver. 1.0 Session 10 Slide 6 of 43
  • 7. Java Programming LanguageInserting Rows The code snippet to create a PreparedStatement object that inserts a row into authors table by passing authors data at runtime is: String str = "INSERT INTO authors(au_id, au_fname, au_lname) VALUES (?, ?, ?)"; PreparedStatement ps = con.prepareStatement(str); ps.setString(1, "1001"); ps.setString(2, "Abraham"); ps.setString(3, "White"); int rt=ps.executeUpdate(); Ver. 1.0 Session 10 Slide 7 of 43
  • 8. Java Programming LanguageUpdating and Deleting Rows The code snippet to modify the state to CA where city is Oakland in the authors table using the PreparedStatement object is: String str = "UPDATE authors SET state= ? WHERE city= ? "; PreparedStatement ps = con.prepareStatement(str); ps.setString(1, "CA"); ps.setString(2, "Oakland"); int rt=ps.executeUpdate(); Ver. 1.0 Session 10 Slide 8 of 43
  • 9. Java Programming LanguageUpdating and Deleting Rows (Contd.) • The code snippet to delete a row from the authors table where author’s first name is Abraham using the PreparedStatement object is: String str = "DELETE FROM authors WHERE au_fname= ? "; PreparedStatement ps = con.prepareStatement(str); ps.setString(1, "Abraham"); int rt=ps.executeUpdate(); Ver. 1.0 Session 10 Slide 9 of 43
  • 10. Java Programming LanguageDemonstration Creating an Application that Uses PreparedStatement Object: Problem Statement: The management of a departmental store has decided to computerize the inventory. You have been asked to create the Product Information application that has an interactive user interface. The application should allow the user to add, update, and delete product information from the product table. Ver. 1.0 Session 10 Slide 10 of 43
  • 11. Java Programming LanguageDemonstration (Contd.) The user interface of the application should be as shown in the following figure: Ver. 1.0 Session 10 Slide 11 of 43
  • 12. Java Programming LanguageDemonstration (Contd.) Solution: The user interface of the application should be as shown in the following figure: – The GUI for the application is created using the java.swing package. The database operations are performed using the PreparedStatement object To solve the above problem, perform the following tasks: Code the application. Compile and execute the application. Ver. 1.0 Session 10 Slide 12 of 43
  • 13. Java Programming LanguageManaging Database Transactions A transaction: Is a set of one or more SQL statements that are executed as a single unit. Is complete only when all the SQL statements in a transaction execute successfully. Maintains consistency of data in a database. Ver. 1.0 Session 10 Slide 13 of 43
  • 14. Java Programming LanguageManaging Database Transactions (Contd.) JDBC API provides support for transaction management. The database transactions can be committed in two ways in the JDBC applications: – Implicit: The Connection object uses the auto-commit mode to execute the SQL statements implicitly. – Explicit: The auto-commit mode is set to false to commit the transaction statement explicitly. The method call to set the auto-commit mode to false is: con.setAutoCommit(false); Ver. 1.0 Session 10 Slide 14 of 43
  • 15. Java Programming LanguageManaging Database Transactions (Contd.) Committing a Transaction: – The commit() method is used to reflect the changes made by the transactions in a database. – The rollback() method is used to undo the changes made in the database after the last commit operation. – You need to explicitly invoke commit() and rollback() methods. Ver. 1.0 Session 10 Slide 15 of 43
  • 16. Java Programming LanguagePerforming Batch Updates A batch: Is a group of update statements that are sent to a database to be executed as a single unit. Reduces network calls between the application and the database. Is a more efficient way as compared to the processing of a single SQL statement. Ver. 1.0 Session 10 Slide 16 of 43
  • 17. Java Programming LanguagePerforming Batch Updates (Contd.) Implementing Batch Updates in JDBC: – The Statement or PreparedStatement interface provides the following methods to create and execute a batch of SQL statements: – void addBatch(): Adds an SQL statement to a batch. – int executeBatch(): Sends a batch of SQL statements to a database for processing and returns the total number of the rows updated. – void clearBatch(): Removes the SQL statements from the batch. Ver. 1.0 Session 10 Slide 17 of 43
  • 18. Java Programming LanguagePerforming Batch Updates (Contd.) • When a Statement object is created to perform batch updates, an empty array is associated with the object. • Multiple SQL statements can be added to the empty array to execute them as a batch. • You also need to disable the auto-commit mode using setAutoCommit(false) while working with batch updates in JDBC. • The executeBatch() method returns an integer array that stores the values of the update count. • The update count is the total number of rows affected when an SQL statement in a batch is processed. Ver. 1.0 Session 10 Slide 18 of 43
  • 19. Java Programming LanguagePerforming Batch Updates (Contd.) The code snippet to create a batch of SQL statements is: con.setAutoCommit(false); Statement stmt=con.createStatement(); stmt.addBatch("INSERT INTO product (p_id, p_desc) VALUES (1001, Printer)"); stmt.addBatch("INSERT INTO product (p_id, p_desc) VALUES (1002, Scanner)"); • The SQL statements in a batch are processed in the order in which the statements appear in a batch. • The method call to execute a batch of SQL statements is: int[] updcount=state.executeBatch(); Ver. 1.0 Session 10 Slide 19 of 43
  • 20. Java Programming LanguagePerforming Batch Updates (Contd.) Exception Handling in Batch Updates: The batch update operations can throw two types of exceptions: – SQLException – BatchUpdateException – The BatchUpdateException class is derived from SQLException class. Ver. 1.0 Session 10 Slide 20 of 43
  • 21. Java Programming LanguagePerforming Batch Updates (Contd.) • The SQLException is thrown by the JDBC API methods, addBatch() or executeBatch(), when problem occurs while accessing a database. • The BatchUpdateException exception is thrown when the SQL statements in the batch cannot be executed due to: Presence of illegal arguments in the SQL statement. Absence of the database table from which you need to retrieve data. • The BatchUpdateException uses an array of the update count to identify the SQL statement that throws the exception. Ver. 1.0 Session 10 Slide 21 of 43
  • 22. Java Programming LanguageCreating and Calling Stored Procedures in JDBC • The java.sql package provides the CallableStatement interface that contains various methods to enable you to call the stored procedures from a database. • The CallableStatement interface is derived from the PreparedStatement interface. Ver. 1.0 Session 10 Slide 22 of 43
  • 23. Java Programming LanguageCreating and Calling Stored Procedures in JDBC (Contd.) Creating Stored Procedure: – Can be created using the CREATE PROCEDURE SQL statement in JDBC applications. – Are of two types: Parameterized Non-parameterized Ver. 1.0 Session 10 Slide 23 of 43
  • 24. Java Programming LanguageCreating and Calling Stored Procedures in JDBC (Contd.) A parameterized stored procedure can accept one or multiple parameters. A parameter of a stored procedure can take any of these forms: IN: Refers to the argument that you pass to a stored procedure. OUT: Refers to the return value of a stored procedure. INOUT: Combines the functionality of the IN and OUT parameters. The INOUT parameter enables you to pass an argument to a stored procedure. The same parameter can also be used to store a return value of a stored procedure. Ver. 1.0 Session 10 Slide 24 of 43
  • 25. Java Programming LanguageCreating and Calling Stored Procedures in JDBC (Contd.) Calling a Stored Procedure without Parameters: – The Connection interface provides the prepareCall() method that is used to create the CallableStatement object to call a stored procedure. – The prepareCall() has the following three forms: CallableStatement prepareCall(String str) CallableStatement prepareCall(String str, int resSetType, int resSetConcurrency) CallableStatement prepareCall(String str, int resSetType, int resSetConcurrency, int resSetHoldability) – The syntax to call a stored procedure without parameters is: { call <procedure_name> }; Ver. 1.0 Session 10 Slide 25 of 43
  • 26. Java Programming LanguageCreating and Calling Stored Procedures in JDBC (Contd.) Calling a Stored Procedure with Parameters: The SQL escape syntax is a standard way to call a stored procedure from a Relational Database Management System (RDBMS) and is independent of the RDBMS. There are two forms of the SQL escape syntax, one that contains result parameter and one that does not. The syntax of the SQL escape syntax is: {[? =] call <procedure_name> [<parameter1>,<parameter2>, ..., <parameterN>]} Ver. 1.0 Session 10 Slide 26 of 43
  • 27. Java Programming LanguageCreating and Calling Stored Procedures in JDBC (Contd.) The placeholders are used to represent the IN, OUT, and INOUT parameters of a stored procedure in the procedure call. The syntax to call a stored procedure with parameters is: { call <procedure_name>(?) }; • You need to set the value of the IN parameters using the set methods before the CallableStatement object is executed. • The syntax to set the value of the IN parameter is: <CallableStatement_object>.setInt(<value>); Ver. 1.0 Session 10 Slide 27 of 43
  • 28. Java Programming LanguageCreating and Calling Stored Procedures in JDBC (Contd.) • If the stored procedure contains OUT and INOUT parameters, these parameters should be registered with the corresponding JDBC types. • The registerOut() method is used to register the parameters. • The prototypes of the registerOut() method are: – registerOut(int index, int stype) – registerOut(int index, int stype, int scale) Ver. 1.0 Session 10 Slide 28 of 43
  • 29. Java Programming LanguageUsing Metadata in JDBC Metadata is the information about data, such as structure and properties of table. The metadata of the employee table includes following information: Names of the columns. Data type of each column. Constraints to enter data values in the table columns. JDBC API provides the following two metadata interfaces to retrieve the information about the database and result set: – DatabaseMetaData interface – ResultSetMetaData interface Ver. 1.0 Session 10 Slide 29 of 43
  • 30. Java Programming LanguageUsing Metadata in JDBC (Contd.) • Using DatabaseMetaData Interface: The DatabaseMetaData interface provides the methods that enable you to determine the properties of a database or RDBMS. An object of DatabaseMetaData is created using the getMetaData() method of the Connection interface. The method call to create an object of the DatabaseMetaData interface is: DatabaseMetaData dm=con.getMetaData(); Ver. 1.0 Session 10 Slide 30 of 43
  • 31. Java Programming LanguageUsing Metadata in JDBC (Contd.) The following table lists the commonly used methods of the DatabaseMetaData interface: Method Description ResultSet getColumns(String Retrieves the information about a catalog, String schema, String column of a database table that is table_name, String column_name) available in the specified catalog. Connection getConnection() Retrieves the database connection that creates the DatabaseMetaData object. String getDriverName() Retrieves the name of the JDBC driver for the DatabaseMetaData object. String getDriverVersion() Retrieves the version of the JDBC driver. Ver. 1.0 Session 10 Slide 31 of 43
  • 32. Java Programming LanguageUsing Metadata in JDBC (Contd.) The methods of the DatabaseMetaData interface: (Contd.) Method Description ResultSet getPrimaryKeys(String Retrieves the information about the catalog, String schema, String primary keys of the database tables. table) String getURL() Retrieves the URL of the database. boolean isReadOnly() Returns a boolean value that indicates whether the database is a read only database. boolean supportsSavepoints() Returns a boolean value that indicates whether the database supports savepoints. Ver. 1.0 Session 10 Slide 32 of 43
  • 33. Java Programming LanguageUsing Metadata in JDBC (Contd.) • Using the ReultSetMetaData Interface: The ReultSetMetaData Interface contains various methods that enable you to retrieve information about the data in a result set. The ResultSet interface provides the getMetaData() method to create an object of the ResultSetMetaData interface. The method call to create an object of the ResultSetMetaData interface: ResultSetMetaData rm=rs.getMetaData(); Ver. 1.0 Session 10 Slide 33 of 43
  • 34. Java Programming LanguageUsing Metadata in JDBC (Contd.) The following table lists the commonly used methods of the ResultSetMetaData interface: Method Description int getColumnCount() Returns an integer indicating the total number of columns in a ResultSet object. String Retrieves the title of the table column corresponding getColumnLabel(int to the index passed as a parameter to this method. column_index) String Retrieves the name of the table column getColumnName(int corresponding to the index passed as a parameter column_index) to this method. int getColumnType(int Retrieves the SQL data type of the table column column_index) corresponding to the index passed as a parameter. Ver. 1.0 Session 10 Slide 34 of 43
  • 35. Java Programming LanguageUsing Metadata in JDBC (Contd.) The methods of the ResultSetMetaData interface: (Contd.) Method Description String Retrieves the name of the database table that getTableName(int contains the column corresponding to the index column_index) passed as a parameter. boolean Returns a boolean value that indicates whether the isAutoIncrement(int table column corresponding to the index passed as a column_index) parameter increments automatically. boolean Returns a boolean value that indicates whether the isCaseSensitive(int table column corresponding to the index passed as a column_index) parameter is case sensitive. Ver. 1.0 Session 10 Slide 35 of 43
  • 36. Java Programming LanguageUsing Metadata in JDBC (Contd.) • The methods of the ResultSetMetaData interface: (Contd.) Method Description boolean isReadOnly(int Returns a boolean value that indicates whether column_index) the column in a ResultSet corresponding to the index passed as a parameter is read only. boolean isWritable(int Returns a boolean value that indicates whether column_index) ResultSet column corresponding to the index passed as a parameter is updatable. Ver. 1.0 Session 10 Slide 36 of 43
  • 37. Java Programming LanguageDemonstration Creating an Application to Retrieve the Information of Database Tables: Problem Statement: – The Manager of New Publishers publishing company, sometimes require the information about the tables of the database used by the company. He is not familiar with the SQL statements, therefore, he has asked you to create an application to determine the total number of columns and the data types of the columns of a given table. The table name has to be specified at the runtime. Ver. 1.0 Session 10 Slide 37 of 43
  • 38. Java Programming LanguageDemonstration (Contd.) Creating an Application to Retrieve the Information of Database Tables (Contd.) Solution: The getColumnName(), getColumnCount(), and getColumnTypeName() methods of the ResultSetMetaData interface are used to develop the above application. To solve the above problem, perform the following tasks: 1. Code the application. 2. Compile and execute the application. Ver. 1.0 Session 10 Slide 38 of 43
  • 39. Java Programming LanguageSummary In this lesson, you have learned: – The PreparedStatement object of the Connection interface allows you to pass runtime parameters to the SQL statements using the placeholders. – There can be multiple placeholders in a single SQL statement. An index value is associated with each placeholder depending upon the position of the placeholder in the SQL statement. – The placeholder stores the value assigned to it until the value is explicitly changed. – A transaction is a set of one or more SQL statements that are executed as a single unit. A transaction is complete only when all the SQL statements in a transaction are successfully executed. Ver. 1.0 Session 10 Slide 39 of 43
  • 40. Java Programming LanguageSummary (Contd.) – If the setAutoCommit() method is set to true the database operations performed by the SQL statements are automatically committed in the database. – The commit() method reflects the changes made by the SQL statements permanently in the database. – The rollback() method is used to undo the effect of all the SQL operations performed after the last commit operation. – A batch is a group of update statements that are sent to a database to be executed as a single unit. You send the batch to a database as a single request using the same Connection object. – The executeBatch() method returns an integer array that stores the update count for all the SQL statements that are executed successfully in a batch. The update count is the number of database rows affected by the database operation performed by each SQL statement. Ver. 1.0 Session 10 Slide 40 of 43
  • 41. Java Programming LanguageSummary (Contd.) – Batch update operations can throw two types of exceptions, SQLException and BatchUpdateException. – The SQLException is thrown when the database access problem occurs. The SQLException is also thrown when a SELECT statement that returns a ResultSet object is executed in a batch. – The BatchUpdateException is thrown when the SQL statement in the batch cannot be executed due to the problem in accessing the specified table or presence of illegal arguments in the SQL statement. – The CallableStatement interface contains various methods that enable you to call the stored procedures from a database. Ver. 1.0 Session 10 Slide 41 of 43
  • 42. Java Programming LanguageSummary (Contd.) The parameters of a stored procedure can take any of these three forms: – IN: Refers to the argument that you pass to a stored procedure. – OUT: Refers to the return value of a stored procedure. – INOUT: Enables you pass an argument to a stored procedure. The same parameters can also be used to pass a return value of a stored procedure. – Metadata is the information about data, such as structure and properties of table. – JDBC API provides two metadata interfaces to retrieve the information about the database and result set, DatabaseMetaData and ResultSetMetaData. – The DatabaseMetaData interface declares methods that enable you to determine the properties of a database or RDBMS. Ver. 1.0 Session 10 Slide 42 of 43
  • 43. Java Programming LanguageSummary (Contd.) – The ResultSetMetaData interface declares methods that enable you to determine information about data in a result set. – The getMetaData() method of the Connection interface enables you to declare the objects of the DatabaseMetaData interface. – The getMetaData() method of the ResultSet interface enables you to create the instance of the ResultSetMetaData interface. Ver. 1.0 Session 10 Slide 43 of 43

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