Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University Data Query Peter McCartney RDIFS Training Workshop Sevilleta LTER October 28-30, 2002

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University Goals Retrieve data from storage Join tables as needed to produce matrix output (denormalize) Transform data to meet analytic needs –Filter, aggregate, select

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University Structured Query Language Universal syntax for querying relational datbases. Provides means for specifying –Attributes required –The source tables and how to join them –Criteria for limiting the result (filtering) –Instructions for ordering the result set

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University A Simple SQL Query SELECT personnel.first_name, personnel.last_name, personnel.country_code FROM personnel WHERE personnel.country_code="usa“

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University A Slightly More Complex Query SELECT personnel.first_name, personnel.last_name, country.country_name, interests.interest_area FROM country INNER JOIN (personnel INNER JOIN interests ON personnel.person_ID = interests.person_ID) ON country.country_code = personnel.country_code WHERE (((personnel.country_code)="usa"))

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University Result

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University Views Views are query statements that are stored in the database. Views return a matrix and may be treated as if they were another table (you can use a view in a query) Only the query statement is stored; the result set is reproduced each time you call the view Views let you hide much of the complicated table joins from your users

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University Query a View SELECT myFirstView.* FROM myFirstView WHERE (((myFirstView.interest_area)="data management"));

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University Querying Remote Databases The beauty of relational databases is that you can use a variety of client applications to query them. Your users do NOT need to learn Access in order to use your database.

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University Accessing Databases Native protocol –Every database has its own native protocol. Applications must be written to this. Open Data Base Connectivity –Windows, Unix, Mac Java Data Base Connectivity –Cross platform –Designed for Java Language

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University A Typical Client Server Connection Database (Access) Application (Excel) Connection Layers (ODBC) Native Syntax Standard SQL Connectivity layer translates applications requests into database‘s native syntax.

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University Define an ODBC Source

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University Query Once an odbc source is defined, you may access it from any application that supports ODBC Excel, SPSS, ArcView, MapInfo, Active Server Pages Range of capabilities and user friendly features will vary

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University Query from Arc View

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University Programming the Web Client side –ECMCA languages – Javascript –Code executed by client browser. All data must be transferred to browser Server side –Template “page” scripting –CGI programs

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University Web Query HTTPD/CGI programs –External program receives form input, generates entire page to be returned. –Server side Java Server scripting –Permits embedding script within html pages –Html code is returned as is, script code is executed by script engine prior to page being returned. –Active Server Pages (MS IIS) –Java Server Pages ( Apache tomcat, BEA WebLogic, IBM WebSphere, Allaire Jrun

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University Three-tiered Query using ASP Declare a connection object and at least one recordset object. Open the connection to your ODBC source Parse the form request parameters Build an sql query Execute the query putting the result in your recordset Access the data in your recordset and write html output to display the data in the page

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University

Central Arizona Phoenix LTER Center for Environmental Studies Arizona State University Lab Assignment Add some data to your database Create some views and store them in your database –(or use the samples at: \\alamillo\inetpub\wwwroot\dbweb) Create an ODBC data source Query your data from Access Create an asp page to display some data following templates: