Murali Mani SQL-PL Interface

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

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

Murali Mani 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} \n"); }

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

Murali Mani 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 (" Test Oracle - 1 \n"); print (" \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 Perl DBI (contd…) Note the usage of DBI->connect Also note configOracle.pm which looks like #!/usr/local/bin/perl package configOracle; use = = qw($host $sid $port $userName $passwd); $host = "oracle.wpi.edu"; $sid = "WPIDBR2"; $port = "1521"; $userName = "mmani"; $passwd = "mmani";

Murali Mani Perl DBI (contd…) $dropTable = $dbh->do ("DROP TABLE studentTemp"); if (!defined ($dropTable)) { print ("error in dropping table studentTemp $DBI::errstr \n"); } $crTable = $dbh->do ("CREATE TABLE studentTemp (num int, name varchar (10))"); if (!defined ($crTable)) { print ("error in creating table studentTemp $DBI::errstr \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 Perl DBI (contd…) $st = $dbh->prepare("SELECT * from studentTemp"); $st->execute(); print (" \n"); while ($data = $st->fetchrow_hashref()) { print " $data->{NUM} $data->{NAME} \n"; } print (" \n"); $st->finish(); $dbh->disconnect();

Murali Mani 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 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 (" Test Oracle - 2 \n"); print (" \n"); print (' '); 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 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 \n"); } } $st = $dbh->prepare("SELECT * from studentTemp"); $st->execute();

Murali Mani Perl with HTML forms (contd..) print (" \n"); print (" number name \n"); while ($data = $st->fetchrow_hashref()) { print " $data->{NUM} $data->{NAME} \n"; } print (" \n"); print <<ENDHTML; Num: Name: ENDHTML print (" \n"); $st->finish(); $dbh->disconnect();

Murali Mani 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 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 Setting up the webserver I will call the root of the installation $TOMCAT_DIR In your.cshrc setenv TOMCAT_DIR /home/mmani/jakarta-tomcat 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 For your.cshrc setenv PATH ${PATH}:${TOMCAT_DIR}/bin setenv CLASSPATH ${CLASSPATH}:${TOMCAT_DIR}/common/lib/servlet- api.jar

Murali Mani Test the webserver Run the script startup.sh Open the page: 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 Servlets: Introduction Write the java code, and compile it. Configure the web server to recognize the servlet class. Restart the web server

Murali Mani 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 Configuring the web server Check $TOMCAT_DIR/webapps/servlets- examples/WEB-INF/web.xml Add the declarations MyTestServlet TestServlet MyTestServlet /servlet/FirstTestServlet

Murali Mani Test the servlet Restart the web server Go to the URL

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

Murali Mani 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 JDBC: Oracle Loading a Driver Class.forName (“oracle.jdbc.driver.OracleDriver”); Establishing a Connection Connection conn = oracle.wpi.edu:1521:WPIDBR2”,, ); Create a Statement Statement stmt = conn.createStatement ();

Murali Mani JDBC with mySQL You need to install the driver mySQL Connector/J from Setenv CLASSPATH /mysql-connector- java stable-bin.jar

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

Murali Mani 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 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 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 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