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Using Oracle JDBC

Using Oracle JDBC. How to Run JDBC on Your Account Communication Mechanism Using Metadata Building a Database Auto Commit v.s Atomic Transaction. # environment variables for Oracle setenv ORACLE_TERM vt100 setenv ORACLE_SID CIS setenv ORACLE_BASE /u01/home/dba/oracle

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Using Oracle JDBC

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  1. Using Oracle JDBC • How to Run JDBC on Your Account • Communication Mechanism • Using Metadata • Building a Database • Auto Commit v.s Atomic Transaction

  2. # environment variables for Oracle setenv ORACLE_TERM vt100 setenv ORACLE_SID CIS setenv ORACLE_BASE /u01/home/dba/oracle setenv ORACLE_HOME /u01/home/dba/oracle/product/7.1.4 setenv NLS_LANG AMERICAN_AMERICA.US7ASCII set path=($ORACLE_HOME/bin $path) # environment variables for Java class files setenv CLASSPATH ./:/pkg/java1.1.6/lib/classes.zip: /pkg/cis550/JDBC/lib/classes111.zip # path to find the Java compiler and VM set path=(/pkg/java-1.1.6/bin . $path ) # path to find libraries for Oracle JDBC drivers setenv LD_LIBRARY_PATH /pkg/cis550/JDBC/lib setenv EPC_DISABLED TRUE

  3. class JdbcTest { public static void main (String args []) throws SQLException, IOException { try { Class.forName ("oracle.jdbc.driver.OracleDriver"); } catch (/*ClassNotFound*/ Exception e) { e.printStackTrace (); } Connection conn = DriverManager.getConnection("jdbc:oracle:oci7:/@cisora"); Statement stmt = conn.createStatement (); ResultSet rset = stmt.executeQuery ("select table_name from tabs"); while (rset.next ()) { System.out.println (rset.getString (1)); }; stmt.close(); conn.close();} }

  4. Database Accessing Mechanism • Registering a database driver. • Using DriverManager to obtain a Connection that represents a database connection. • Sending a SQL statement to the database using Statement. • Retrieving the query result with a ResultSet.

  5. Using Metadata Look into the database itself and its contents. Class.forName ("oracle.jdbc.driver.OracleDriver"); Connection conn= DriverManager.getConnection("jdbc:oracle:oci7:/@cisora"); Statement stmt = conn.createStatement (); ResultSet rset = stmt.executeQuery(sql_query_string); ResultSetMetaData metadata = rset.getMetaData(); int numcols = metadata.getColumnCount(); // how many columns String labl1 = metadata.getColumnLabel(1); // get the first label int size = metadata.getColumnDisplaySize(1); // get the column width

  6. insertSailor = conn.prepareStatement(“INSERT INTO Sailor VALUES(?, ?, ?); //sailor_name, sailor_rating, sailor_age Building a Database • Repeatedly use INSERT INTO • Increase the efficiency by providing PreparedStatement: database interprets the prepared statement and creates its template just once.

  7. Atomic Transactions • A newly-created Connection is “auto commit” • Each update is as a separate transaction and automatically committed to the database. • How to “group” several updates into a single “atomic” transaction? • Take Connection out of “auto commit” mode. • Explicitly call commit() to a batch of transactions • call rollback() to abort a batch of transactions.

  8. Class.forName ("oracle.jdbc.driver.OracleDriver"); Connection conn= DriverManager.getConnection("jdbc:oracle:oci7:/@cisora"); conn.setAutoCommit(FALSE); conn.setTransactionIsolation(Connection.TRANSACTION_READ_COMMITTED); Statement stmt = conn.createStatement (); try{ stmt.executeUpdate(sql_str_Insert_Account_Table); stmt.executeUpdate(sql_str_Create_History_Table); stmt.executeUpdate(sql_str_Insert_History_Table); conn.commit(); // commit the updates } catch(SQLException e) { conn.rollback(); // removes all updates from the database }

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