JDBC Session 2 Tonight’s topics: 1.Prepared Statements 2.Transaction Processing 3.Callable Statements & Stored Procedures 4.Scrollable & Updatable Result Sets 5.Mapping SQL Data Types to Java 6.Batch Processing & SQL MetaData 7.Lab

JDBC Session 2 Interface PreparedStatement Extends Statement - More flexible - More efficient See PreparedSQL.java for use in a SELECT query For more info: PreparedStatementPreparedStatement Prepared Statements

JDBC Session 2 Operation successful: Commit the transaction Operation failed: Roll back the transaction Java transaction processing: Method setAutoCommit Method commit Method rollback See InsertSQL.java for use in an INSERT query Transaction Processing

JDBC Session 2 Interface CallableStatement Extends Statement Used to invoke a Stored Procedure Stored Procedures Store SQL statements in a database Advantages –Speed of execution –Security –Encapsulation –Reuse Callable Statements & Stored Procedures (p.1)

JDBC Session 2 Stored Procedures Oracle – written in PL/SQL SQL Server – written in T-SQL DB2 - ??? Access – possible using “Data Access Objects” (DAO) but beyond the scope of this class Callable Statements & Stored Procedures (p.2)

JDBC Session 2 Oracle Example Callable Statements & Stored Procedures (p.3) CREATE OR REPLACE PROCEDURE insert_employee (p_eid IN CHAR,p_fname IN VARCHAR2,p_lname IN VARCHAR2,p_age IN NUMBER,p_entrydate OUT DATE ) IS BEGIN p_entrydate := SYSDATE; INSERT INTO employee (eid, fname, lname, age, entrydate) VALUES (p_eid, p_fname, p_lname, p_age, p_entrydate); END insert_employee;... CallableStatement stmt = con.prepareCall( "{call insert_employee(?, ?, ?, ?, ?)}"); stmt.setString(1, " "); stmt.setString(2, "John"); stmt.setString(3, "Smith"); stmt.setInt(4, 30); stmt.registerOutParameter(5, Types.DATE); stmt.execute(); System.out.println("entry date = " + stmt.getDate(5));...

JDBC Session 2 Scrollable & Updatable Result Sets (p.1) From the API: ResultSet Field Summary static int TYPE_FORWARD_ONLY(default) The constant indicating the type for a ResultSet object whose cursor may move only forward. static int TYPE_SCROLL_INSENSITIVE The constant indicating the type for a ResultSet object that is scrollable but generally not sensitive to changes made by others. static int TYPE_SCROLL_SENSITIVE The constant indicating the type for a ResultSet object that is scrollable and generally sensitive to changes made by others. static int CONCUR_READ_ONLY(default) The constant indicating the concurrency mode for a ResultSet object that may NOT be updated. static int CONCUR_UPDATABLE The constant indicating the concurrency mode for a ResultSet object that may be updated. Use Statement stmt = con.createStatement( ResultSet.TYPE_SCROLL_INSENSITIVE, ResultSet.CONCUR_UPDATABLE); ResultSet rs = stmt.executeQuery("SELECT a, b FROM TABLE2"); // rs will be scrollable, will not show changes made by others, // and will be updatable

JDBC Session 2 Scrollable & Updatable Result Sets (p.2) Updatable Result Sets Using updateXXX methods The updateXXX methods may be used in two ways: 1.to update a column value in the current row. In a scrollable ResultSet object, the cursor can be moved backwards and forwards, to an absolute position, or to a position relative to the current row. The following code fragment updates the NAME column in the fifth row of the ResultSet object rs and then uses the method updateRow to update the data source table from which rs was derived. rs.absolute(5);// moves the cursor to the fifth row of rs rs.updateString("NAME", "AINSWORTH"); // updates the NAME column of row 5 to be AINSWORTH rs.updateRow(); // updates the row in the data source 2.to insert column values into the insert row. An updatable ResultSet object has a special row associated with it that serves as a staging area for building a row to be inserted. The following code fragment moves the cursor to the insert row, builds a three-column row, and inserts it into rs and into the data source table using the method insertRow. rs.moveToInsertRow(); // moves cursor to the insert row rs.updateString(1, "AINSWORTH"); // updates the first column of the insert row to be AINSWORTH rs.updateInt(2,35); // updates the second column to be 35 rs.updateBoolean(3, true); // updates the third row to true rs.insertRow(); rs.moveToCurrentRow(); Scrollable Result Sets See MurachBooks for use

JDBC Session 2 Mapping SQL Data Types to Java (p.1) Java Data Type  JDBC Data Type  Data Base Data Type

JDBC Session 2 Mapping SQL Data Types to Java (p.2) Microsoft Access Data Types

JDBC Session 2 Mapping SQL Data Types to Java (p.3) Conversions by ResultSet.getXXX "x" means that the method can retrieve the JDBC type "X" means that the method is recommended for retrieving the JDBC type See: Mapping SQL - Java Types Mapping SQL - Java Types

JDBC Session 2 Batch Processing & SQL MetaData Batch Processing Allows multiple update statements (INSERT, UPDATE, DELETE) in a single data base request See Movies/ CreateMovieTables.java SQL Metadata See Movies/ QueryMovieTables.java