Data Access Standards. ODBC, OLE DB, and ADO Introduction. History of ODBC. History of ODBC 4/24/2016

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1 Data Access Standards ODBC, OLE DB, and ADO Introduction I Gede Made Karma The reasons for ODBC, OLE DB, and ADO are to provide a standardized method and API for accessing and manipulating Data from different databases. ODBC (Open Database Connectivity) is the most basic and common standard interface for accessing databases. History of ODBC History of ODBC Microsoft releases first version of ODBC in 1992 Based on the SAG CLI, which was created by the SQL Access Group ODBC 2.0 SDK was released in 1994 ODBC 3.0 SDK was release in 1996 Typical ODBC Architecture How ODBC Works? ODBC inserts a middle layer called a Client Driver Purpose of the Client Driver is to translate the applications queries into commands that the DBMS understands 1

2 Other Parts of the Architecture Application calls functions defined in the ODBC API to access a data source Driver Manager implements the ODBC API and provides information to the application Database contains all the data Setting Up a Data Source in Windows A data source is just a database that ODBC connects to This allows the person to change database types without any changes to the program Step 1. Get a database. Using access for this example because it s on this computer Setting Up a Data Source in Windows Step 2. Open Windows ODBC Manager Control Panel / Administrative Tools / Data Sources (ODBC). Step 3. Click Add, Select the Microsoft Access Driver (.mdb) and click Finish Step 4. Type a name, Select a database or create one and click OK. You re done. Celebrate. Setting Up a Data Source in Windows Obviously, all of this can be done in UNIX or Linux but how to do it differs. ODBC is developed by third parties for UNIX and creating a data source differs for each. First, import the packages needed to use ODBC. This is so Perl knows what you re talking about later use Win32::ODBC; Next, we need to connect to the database. Here is where you need to know the name of the data source. $db = new Win32::ODBC( YOUR_FRIGGIN_DATA_SOURCE_ NAME_HERE ); Now you can make SQL statements. $stmt = INSERT INTO diskdrives (food) VALUES ( pudding { food }); To make the statement execute in the database, do this $db->sql($stmt); It s easy to insert pudding into diskdrives. 2

3 But, lets say you want to get data from the database. You cant. Just kidding. Do this: $stmt = SELECT * FROM interesting_computer_books ; $db->sql(stmt); If for some strange reason there s actually items in the table interesting_computer_books, do the following to get them. Loop through the results while ($db->fetchrow()) { ($title, $author) = $db->data( title, author ) // Do what you want with the data here $bookburner->burn($title, $author); } Once you re all done with the database, close the connection $db->close(); So, that s it. Imagine how long this would have taken without ODBC. -Open Database Connectivity -Based on SQL Access Group s Call Level Interface specification -Invented by Microsoft in the early nineties -Microsoft realized a problem and decided to do something about it -People who wrote programs that interacted with databases had to write different code for each database - ODBC gives programmer the ability to write single source code in ODBC standards. - ODBC then does the work to gain access to different types of databases if necessary. - There are essentially four parts to ODBC: 1. Application Coded by the programmer. Communicates with ODBC 2. Driver Manager Provides the ODBC interface to the application Also responsible for loading the correct database driver that is desired by the application 3. Database Driver Handles translation between ODBC s API, and each database that it connects to 4. Database The database in which ODBC communicates with (Access, Oracle, etc.) 3

4 The four parts that make up ODBC: Advantages: Allows access to different types of databases Uniform way of retrieving information Highly efficient Low memory requirements Disadvantages Complex and steep learning curve All data in database must look like a relational database ODBC changed the way people code their programs that have to interact with databases. The efficiency of programmers in the business world has increased due to ODBC because they no longer are wasting time to create multiple copies of a program. ODBC has vastly improved the way programmers deal with databases. ODBC Conformance Levels Application Programming Interface Core Level 1 Level 2 SQL Grammar Minimum Core Extended Establishing an ODBC Datasource In Control Panel, Administrative Options, there is an icon for ODBC Datasources 4

5 ODBC Datasources ODBC Datasources File Data Source A physical file which can be shared among users on a single computer. System Data Source A source of data that is local to a single computer. Can be remotely accessed through the computer. User Data Source Available only to the user who created it. 5

6 Microsoft OLE DB Creates an Object Oriented Programming model on top of ODB (and other drivers) to allow a programmatic access to database through a Object Oriented interface. Using Microsoft OLE DB ADO and ADO.Net Client Application Code OLE DB Consumer ADO Db Client Application that uses OLE DB OLE DB OLE DB Providers MSDASQL.DLL SQLOLEDB.DLL MSJTOR35.DLL ODBC Data Sources SQL Server MDB Files One level of abstraction higher that OLE DB. Basic object model that overlies the more complex OLE DB model. Basic Definition Namespace In programming a namespace encapsulates other name spaces, programming classes, and other functions that are common and uniquely named. ADO.Net Namespaces The ADO.NET Object Model Objects of System.Data.NET data providers ADO.NET namespace hierarchy Organizes the object model Includes: System.Data System.Data.OleDb System.Data.Common System.Data.SqlClient System.Data.SqlTypes 6

7 The System.Data Namespace System.Data Classes.Common Contains classes shared by both.sqlclient SqlCommand SqlConnection SqlDataReader SqlDataAdapter System.Data.OleDb OleDbCommand OleDbConnection OleDbDataReader OleDbDataAdapter System.Data DataSet - In-memory cache of data DataTable - In-memory cache of a database table DataRow - Used to manipulate a row in a DataTable DataColumn - Used to define the columns in a DataTable DataRelation - Used to relate 2 DataTables to each other DataViewManager - Used to create views on DataSets Using ADO.Net Classes Connection Object ODBCConnection OleDBConnection SQLConnection ConnectionString property defines the information to allow connecting to a database. // create a connection string Connection Class String constr="provider=microsoft.jet.oledb.4.0;" + "Data Source=NWIND_RW.MDB"; // create a connection object using the connection string OleDbConnection aconn = new OleDbConnection(conStr); // open the connection aconn.open(); // Perform database actions aconn.close(); 7