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ECMM6018 Enterprise Networking For Electronic Commerce Tutorial 6

ECMM6018 Enterprise Networking For Electronic Commerce Tutorial 6. CGI/Perl and databases. Databases. Defn: A database is a collection of data that is organized so that its contents can easily be accessed, managed, and updated. [1] Different types of databases

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ECMM6018 Enterprise Networking For Electronic Commerce Tutorial 6

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  1. ECMM6018 Enterprise Networking For Electronic CommerceTutorial 6 CGI/Perl and databases

  2. Databases • Defn: A database is a collection of data that is organized so that its contents can easily be accessed, managed, and updated.[1] • Different types of databases • i.Relational Database: Stores data in the form of related tables • ii.Object Oriented Programming Database: This has the data defined in objects classes and sub classes. • Some of the Databases in use: IBM's DB2, Microsoft's Access, MySQL, Postgresql and products from Oracle, Sybase, and Computer Associates. • [1] http://searchdatabase.techtarget.com/sDefinition/0,,sid13_gci211895,00.html

  3. Databases Continued • For DBMS a record is collection of fields each field containing one entry • In databases records are also known as tuples • Recordset – collection of records returned which match the query entered.

  4. Figure 1: Showing table in database

  5. Figure2: Showing recordset returned for a query

  6. Structured Query Language (SQL) • A programming language, that allows access to a database. • SQL Data Manipulation Language (DML) • SQL Data Definition Language (DDL)

  7. SQL Data Manipulation Language (DML) • This allows us to either extract, insert, delete or update data in the database • SELECT - extracts data from a database table • UPDATE - updates data in a database table • DELETE - deletes data from a database table • INSERT INTO - inserts new data into a database table

  8. SELECT SYNTAX • SELECT column_name(s) FROM table_name • WHERE clause: This allows us to conditionally select data from a table based upon some criteria • SELECT column FROM table WHERE column operator value e.g. Select * from nur

  9. UPDATE SYNTAX • UPDATE table_name SET column_name = new_value WHERE column_name = some_value e.g. update #period# set period ='#period#', Primary='#form.Primary#',Last1='#form.Last1#', First1'#form.First1#',Last2='#form.Last2#',First2='#form.First2#',editor_last1='#editor_last1# where key=#form.key#

  10. DELETE and INSERT SYNTAX • DELETE FROM table_name WHERE column_name = some_value e.g. delete from nur where l_name='zincir' • INSERT INTO table_name VALUES (value1, value2,....) e.g. insert into nur (l_name,f_name) values ('lastname1','firstname1')

  11. SQL Data Definition Language (DDL) • This allows us to create or delete tables in the database. • CREATE TABLE - creates a new database table • ALTER TABLE - alters (changes) a database table • DROP TABLE - deletes a database table

  12. DDL SYNTAX • CREATE TABLE table_name ( column_name1 data_type, column_name2 data_type, ....... ) • ALTER TABLE table_name ADD column_name datatype • ALTER TABLE table_name DROP COLUMN column_name

  13. Database connection strings • ODBC (Object Database Connectivity) – An application interface for accessing a database. Makes it possible to assess data from any application irrelevant of the underlying DBMS used. It carries out this task by inserting a middle layer known as a driver between the application and the DBMS. The role of this is to convert application's data queries into commands that the DBMS understands.[1] It is also language independent. • JDBC [1] http://www.webopedia.com/TERM/O/ODBC.html

  14. Connection String in Perl • $dbh=DBI->connect('dbi:Oracle' ,$username,$password); • DBI = Database Independent Module, allows for access to a supported SQL database

  15. Using a database through the DBI module • Connect to the database • Prepare the SQL statement and return a statement handle • Using the Statement handle, Execute the SQL statement • If the SQL statement is a SELECT, use the Statement handle to get the SELECTed records • Close the statement handle • Close the connection

  16. Useful Links • http://www.suite101.com/article.cfm/perl/67813 • http://www.saturn5.com/~jwb/dbi-examples.html

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