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SQL-PL Interface

SQL-PL Interface. Some Possible Options. Web Interface Perl /CGI with Oracle/mySQL Install your own web server and use servlets with JDBC and Oracle/mySQL Non-Web Interface JDBC with Oracle/mySQL Also other options like embedded SQL. Perl Features (from Mike Ciaraldi’s slides).

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SQL-PL Interface

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  1. SQL-PL Interface Murali Mani

  2. Some Possible Options • Web Interface • Perl /CGI with Oracle/mySQL • Install your own web server and use servlets with JDBC and Oracle/mySQL • Non-Web Interface • JDBC with Oracle/mySQL • Also other options like embedded SQL Murali Mani

  3. Perl Features (from Mike Ciaraldi’s slides) • Created around 1987 by Larry Wall. • A scripting language. • Widely used. • Utilities • Web server programs (CGI). • Quick reference to Perl Murali Mani

  4. Perl – Hello World #!/usr/local/bin/perl use CGI::Carp qw(fatalsToBrowser warningsToBrowser); print "Content-type: text/html\n\n"; print ("<html><head><title>Hello World Script</title></head>\n"); print ("<body>\n"); print ("<h1>Hello World !!!!</h1>\n"); print ("</body></html>\n"); Murali Mani

  5. Perl – Hello World (Again !!) #!/usr/local/bin/perl use CGI::Carp qw(fatalsToBrowser warningsToBrowser); print "Content-type: text/html\n\n"; print <<ENDHTML; <html><head><title>Hello World Script</title></head> <body> <h1>Hello World !!!!</h1> </body></html> ENDHTML Murali Mani

  6. Perl – printing out environment variables #!/usr/local/bin/perl -w use CGI::Carp qw(fatalsToBrowser warningsToBrowser); print "Content-type: text/html\n\n"; foreach $key (keys %{ENV}) { print ("$key = $ENV{$key}<br>\n"); } Murali Mani

  7. Perl DBI (Data Base Interface) module • Module that supports functions for connecting to pretty much any DBMS software – Oracle, mySQL, Microsoft databases through ODBC etc. Murali Mani

  8. How does Perl DBI work? (Image from OReilly) Murali Mani

  9. Perl DBI: Main functions #!/usr/local/bin/perl use CGI::Carp qw(fatalsToBrowser warningsToBrowser); use DBI; use configOracle; print "Content-type: text/html\n\n"; print ("<html><head><title>Test Oracle - 1</title></head>\n"); print ("<body>\n"); if ($ENV{HTTP_ACCEPT}) { $ENV{ORACLE_HOME} = "/usr/local/oracle/product/11.1.0/db_1"; } $dbh = DBI->connect ("DBI:Oracle:host=$host;sid=$sid;port=$port", $userName, $passwd) || die "Database connection not made: $DBI::errstr"; Murali Mani

  10. Perl DBI (contd…) • Note the usage of DBI->connect • Also note configOracle.pm which looks like #!/usr/local/bin/perl package configOracle; use Exporter; @ISA = ('Exporter'); @EXPORT = qw($host $sid $port $userName $passwd); $host = "oracle.wpi.edu"; $sid = "WPIDBR2"; $port = "1521"; $userName = "mmani"; $passwd = "mmani"; Murali Mani

  11. Perl DBI (contd…) $dropTable = $dbh->do ("DROP TABLE studentTemp"); if (!defined ($dropTable)) { print ("error in dropping table studentTemp $DBI::errstr<br>\n"); } $crTable = $dbh->do ("CREATE TABLE studentTemp (num int, name varchar (10))"); if (!defined ($crTable)) { print ("error in creating table studentTemp $DBI::errstr<br>\n"); } $rows = $dbh->do ("INSERT INTO studentTemp VALUES (1," . $dbh->quote ("Matt") . ")"); $rows = $dbh->do ("INSERT INTO studentTemp VALUES (2," . $dbh->quote ("Greg") . ")"); Murali Mani

  12. Perl DBI (contd…) $st = $dbh->prepare("SELECT * from studentTemp"); $st->execute(); print ("<table>\n"); while ($data = $st->fetchrow_hashref()) { print "<tr><td> $data->{NUM} </td><td> $data->{NAME} </td></tr>\n"; } print ("</table></body></html>\n"); $st->finish(); $dbh->disconnect(); Murali Mani

  13. Perl with mySQL • Everything stays the same except for the connect string – $dbh = DBI->connect ("DBI:mysql:$schema:$server", $userName, $passwd) || die "Database connection not made: $DBI::errstr"; Murali Mani

  14. Perl with HTML forms and Oracle #!/usr/local/bin/perl use CGI::Carp qw(fatalsToBrowser warningsToBrowser); use DBI; use configOracle; use CGI ":standard"; print "Content-type: text/html\n\n"; print ("<html><head><title>Test Oracle - 2</title></head>\n"); print ("<body>\n"); print ('<form method=post action=testOracle2.pl>'); if ($ENV{HTTP_ACCEPT}) { $ENV{ORACLE_HOME} = "/usr/local/oracle/product/11.1.0/db_1"; } $dbh = DBI->connect ("DBI:Oracle:host=$host;sid=$sid;port=$port", $userName,$passwd) || die "Database connection not made: $DBI::errstr"; Murali Mani

  15. Perl with HTML forms (contd..) if (defined (param ("submit"))) { $rows = $dbh->do ("INSERT INTO studentTemp VALUES (" . $dbh->quote (param ("a1")) . ", " . $dbh->quote (param ("a2")) . ")"); if (! defined ($rows)) { print ("error inserting $DBI::errstr<br>\n"); } } $st = $dbh->prepare("SELECT * from studentTemp"); $st->execute(); Murali Mani

  16. Perl with HTML forms (contd..) print ("<table border=1>\n"); print ("<tr><th>number</th><th>name</th></tr>\n"); while ($data = $st->fetchrow_hashref()) { print "<tr><td> $data->{NUM} </td><td> $data->{NAME} </td></tr>\n"; } print ("</table>\n"); print <<ENDHTML; <br><br> Num: <input type="text" name="a1"><br> Name: <input type="text" name="a2"><br><br> <input type="Submit" name="submit" value="Enter Information"/> ENDHTML print ("</form></body></html>\n"); $st->finish(); $dbh->disconnect(); Murali Mani

  17. Java Servlets • Steps • Install a web server, such as Apache Tomcat • Learn about servlets • Learn about HTML forms • Learn how to use JDBC • Integrate them into your project. Murali Mani

  18. Installing a web server • Download it from jakarta.apache.org/tomcat • You might need about 50 MB of space for the installation • For example, get the .tar.gz file (You may want to keep it in the temp directory, rather than your personal disk space). • tar –xvzf file.tar.gz (untar it directly without unzipping it to save space). Murali Mani

  19. Setting up the webserver • I will call the root of the installation $TOMCAT_DIR • In your .cshrc • setenv TOMCAT_DIR /home/mmani/jakarta-tomcat-5.0.18 • Check the file $TOMCAT_DIR/conf/server.xml • You will see a line <Connector port=“8080” • You can renumber the port, say between 1200 and 20000 • For your .cshrc • setenv PATH ${PATH}:${TOMCAT_DIR}/bin • setenv CLASSPATH ${CLASSPATH}:${TOMCAT_DIR}/common/lib/servlet-api.jar Murali Mani

  20. Test the webserver • Run the script startup.sh • Open the page: http://ccc2.wpi.edu:1200 • You ran the startup.sh from ccc2 • Your web server is configured to port 1200 (default was 8080) • To check for errors etc, check $TOMCAT_DIR/logs • To shut down, run the script shutdown.sh • Check what processes are running: ps -u mmani • Kill unnecessary Java processes: killall java Murali Mani

  21. Servlets: Introduction • Write the java code, and compile it. • Configure the web server to recognize the servlet class. • Restart the web server Murali Mani

  22. First Java Servlet • Check the directory $TOMCAT_DIR/webapps/servlets-examples/WEB-INF/classes • There exist example servlets here • Create a test servlet with the method doGet • Compile it, let our test servlet be TestServlet.class Murali Mani

  23. Configuring the web server • Check $TOMCAT_DIR/webapps/servlets-examples/WEB-INF/web.xml • Add the declarations <servlet> <servlet-name>MyTestServlet</servlet-name> <servlet-class>TestServlet</servlet-class> </servlet> <servlet-mapping> <servlet-name>MyTestServlet</servlet-name> <url-pattern>/servlet/FirstTestServlet</url-pattern> </servlet-mapping> Murali Mani

  24. Test the servlet • Restart the web server • Go to the URL http://ccc2.wpi.edu:1200/servlets-examples/servlet/FirstTestServlet Murali Mani

  25. JDBC: CLI (Call Level Interface) • JDBC (Java Database Connetivity) is a standard API for connecting to databases from Java programs (such as servlets). • Different vendors provide JDBC drivers implementing the JDBC API for different DBMS: Oracle, mySQL etc Murali Mani

  26. Java Code with JDBC • Steps • import java.sql.* • Load a driver instance • Establish Connection • Create a Statement • Query Murali Mani

  27. JDBC with Oracle • JDBC driver comes with database server • Check $ORACLE_HOME/jdbc/Readme.txt • setenv CLASSPATH ${CLASSPATH}:${ORACLE_HOME}/jdbc/lib/ojdbc6.jar Murali Mani

  28. JDBC: Oracle • Loading a Driver Class.forName (“oracle.jdbc.driver.OracleDriver”); • Establishing a Connection Connection conn = DriverManager.getConnection(“jdbc:oracle:thin:@oracle.wpi.edu:1521:WPIDBR2”, <userName>, <password>); • Create a Statement Statement stmt = conn.createStatement (); Murali Mani

  29. JDBC with mySQL • You need to install the driver mySQL Connector/J from www.mysql.com • Setenv CLASSPATH <dir>/mysql-connector-java-3.1.0-stable-bin.jar Murali Mani

  30. JDBC: mySQL • Loading a Driver Class.forName (“com.mysql.jdbc.Driver”); • Establishing a Connection Connection conn = DriverManager.getConnection (“jdbc:mysql://mysql.wpi.edu/<dbName>”, <userName>, <password>); • Create a Statement Statement stmt = conn.createStatement (); Murali Mani

  31. Queries using JDBC • Queries: SQL DDL String sql = “CREATE TABLE a (a1 int, a2 int)”; stmt.executeUpdate (sql) • Queries: SQL DML (Updates) String sql = “INSERT INTO a values (1, 1)”; stmt.executeUpdate (sql) • Queries: SQL DML (Retrieval) String sql = “SELECT * FROM a”; ResultSet r = stmt.executeQuery (sql); Murali Mani

  32. JDBC Result Set: Iteration • We can iterate over a result set, r as: /* fetch the next tuple from r and ensure that it is not empty */ while (r.next ()) { System.out.println (“a1 = “ + r.getString (“a1”)); } Murali Mani

  33. Close the statement and connection try { stmt.close (); } catch (SQLException sqlEx) { System.out.println (“Could not close statement:” + sqlEx.toString ()); try { conn.close (); } catch (SQLException sqlEx) { System.out.println (“Could not close connection:” + sqlEx.toString ()); Murali Mani

  34. Using Servlets with JDBC • Ensure that the JDBC driver can be downloaded by our servlet. • The servlet sees only the classes available at • $TOMCAT_DIR/shared/lib • $TOMCAT_DIR/common/lib • Create a symbolic link, for example, for Oracle JDBC driver, from the directory $TOMCAT_DIR/shared/lib ln –s $ORACLE_HOME/jdbc/lib/ojdbc6.jar ojdbc6.jar Murali Mani

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