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Interacting With Data - PowerPoint PPT Presentation

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Interacting With Data

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  1. Interacting With Data Week 8 Connecting to the database Creating recordsets Interacting with the database

  2. Database - Data Table Table Name Students Column (Field) StudentnoNameAddressPhone Row (Record) 11462534 White 9 White St 783-5643 44376789 Brown 6 Brown Rd 656-2222 23390765 Smith 2 Smith St 222-5858 Information is added to a data table on a Row by Row basis Table names and Column names are case sensitive

  3. How Data Flows ODBC (Open Database Connectivity) (Translates client request so DBMS understands what the client wants) Client Browser Sends Recordset request by way of Connection Object Sends and receives Query request by way of Recordset Object Database Management System(Applies rules and searches for data) Data Tables (contains all information) Search for Data (SQL query) Create recordset based on data found Recordsets (contains copy of information requested by client)

  4. How Data Flows ODBC Connection Interpreter (DSN)(Translates client request so DBMS understands what to do) • Open Database Connectivity provides a standard software interface to different database management systems (DBMS). • Software applications can communicate with different DBMSs without altering their applications by using drivers provided by Database system vendors • “a standard database access method developed by the SQL Access group in 1992. The goal of ODBC is to make it possible to access any data from any application, regardless of which database management system (DBMS) is handling the data. ODBC manages this by inserting a middle layer, called a database driver, between an application and the DBMS. The purpose of this layer is to translate the application's data queries into commands that the DBMS understands. For this to work, both the application and the DBMS must be ODBC-compliant -- that is, the application must be capable of issuing ODBC commands and the DBMS must be capable of responding to them. Since version 2.0, the standard supports SAG SQL. http://www.ozekisms.com/high-performance-sms-gateway/terms-and-definitions/index_p_php_q_ow_page_number_e_110opt.html

  5. How Data Flows • DSNs (data source name) are set up to use drivers, either by; 1) accessing the ODBC applet in the control panel or, 2) writing a DSN-less connection string (handy when you do not have access to the control panel or when the O/S does not have a control panel) • A Connection Object is created which allows the application to connect to the database System

  6. How Data Flows Creating The Connection Object • The Connection Object can be created either as a DSN or DSN-less connection DSN Connection <% ‘create the object (DSN already set in the control panel) that will connect to the database Set conn = CreateObject (“ADODB.Connection”) ‘ open the connection conn.Open “INT213con” %> Note: I will discuss this topic in nest week. DSN-less Connection <% ‘create the object without DSN being setup in control panel Set conn = CreateObject (“ADODB.Connection”) ‘ create the connection conn.ConnectionString="DRIVER={Microsoft Access Driver (*.mdb)};" &_ "DBQ=C:\Inetpub\wwwroot\INT213db.mdb“ ‘Open the connection conn.Open %>

  7. Recordset Object Recordsets (contains information requested by client) • Recordset Objectsends a query to the database system using the Connection Object. • A recordset is a data structurethat consists of a group of databaserecords, and can either come from a base table or as the result of a query to the table.http://en.wikipedia.org/wiki/Recordset • The DBMS processes the query and returns the data requestedin the form of Rows and Columns (just like an Excel spreadsheet). • The Recordset and the data it contains is a copy (snapshot) of the data from the data tables. It is held in RAM on the client system. This data can be displayed, altered, deleted, etc. Any changes are sent back to the server using the Recordset Object • The actual data tables will not be affected by changes until the Recordset is written back to the Data Tables.