Java and Databases.ppt

1、Java and Databases,CS-328 Dick Steflik,Database Drivers,Think of a database as just another device connected to your computer like other devices it has a driver program to relieves you of having to do low level programming to use the database the driver provides you with a high level api to the data

2、base,ODBC,Open Data Base Connectivity Developed by Microsoft for the Windows platform as the way for Windows applications to access Microsoft databases (SQL Server, FoxPro, Access) Has become an industry standard Most data base vendors supply native, odbc, and jdbc drivers for their data base produc

3、ts,JDBC Architecture,Java Application,JDBC API,Data Base Drivers,Access,SQLServer,DB2,Informix,MySQL,Sybase,JDBC Driver Types,Type 1JDBC-ODBC Bridge Type 2 Native API, partially java Type 3 JDBC Network Driver, partially java Type 4 100% Java,Type 1 Drivers,Translate JDBC into ODBC and use Windows O

4、DBC built in drivers ODBC must be set up on every client driver must be physically on each machine for both java applications and applets for server side servlets ODBC must be set up on web server driver sun.jdbc.odbc.JdbcOdbc provided by JavaSoft with JDK,Type 1 Driver (cont.),Client,JDBC-ODBC,ODBC

5、,DB,Vendor Library,Type 2 Drivers,Converts JDBC to data base vendors native SQL calls like Type 1 drivers; requires installation of binaries on each client,Type 2 Drivers (cont.),Client,JDBC,Vendor Library,DB,Type 3 Drivers,Translates JDBC to a DBMS independent network protocol Typically talks direc

6、tly with a middleware product which in turn talks to the RDBMS Jaguar, DBAnywhere, SequeLink Most flexible driver type all java,Type 3 Drivers (cont.),Client,JDBC,Vendor Middleware,DB,Tier 1,Tier 2,Tier 3,Type 4 Drivers,Converts JDBC directly to native API used by the RDBMS compiles into the applica

7、tion , applet or servlet; doesnt require anything to be installed on client machine, except JVM handiest driver type,Type 4 Drivers (cont.),Client,JDBC,DB,Structured Query Language,Developed by C. Date for Relational Data Base Management Systems (RDBMS) Simple Declarative Language has no program con

8、trol statements,SQL,Two categories of commands Data Manipulation Commands deal with: RETRIEVING DATA MAINTAINING DATA (ADDING, UPDATING,DELETING Data Definition Commands DEAL WITH: CREATING DATABASE OBJECTS (TABLES,VIEWS) Object organization and attributes,Referential Integrity,Rules to insure that

9、table data stays accurate and accessible rows in a table should be unique one column should contain no duplicate data primary key column values cannot contain repeating groups or arrays null is different than space and zero, 2 null values are not considered equal,Data Manipulation Commands,Select -

10、query and display data from a database Insert - a new row into a table Update - modify a column in a table Delete a row from a table,Select,Select (column list) from (sources) where (conditions) order by (ocolumn list) column list - comma separated list of names of columns to be in output Ex. ssn ,

11、lastname , firstname,gpa can contain literals to be included in output Ex. Ssn,”,lastname,”,firstname sources - name(s) of table(s) to retrieve data from conditions (optional) - conditions for selections lastname like “S%” (lastname = “Steflik) and (firstname like “R%”) ocolumn list (optional)- list

12、 of columns that output should be ordered by Ex select * from student select lastname,fristname from student where gpa 3.0 select lastname,firstname from student order by lastname,firstname,Select - joined tables,Two tables may be joined and viewed as a single data source is the both have a common c

13、olumn suppose we have 2 tables: Inventory and category and each has a column called catg_code In category catg_code is unique and is the primary key,Select - joined tables (cont.),P_no,Catg_code,qty,Catg_code,descr,Inventory,Category,join,Select - joined tables (cont.),To retrieve all of the part nu

14、mbers and the name of the category to which the part belongs: select inventory.p_no category.descr from inventroy , category select a.p_no,” “,b.descr from a inventory , b category,Insert,Add a row to a table insert into category values(“IGN”,”Ignition System”) use jdbc execute Update method ex. Stm

15、t.executeUpdate(“insert into Category values(IGN,Ignition System)”);,Update,Modify an existing row in a table update category set descr = “Ignition Subsystem” where catg_code = “IGN” Use jdbc executeUpdate method String s = “update category set descr = Ignition Subsystem where catg_code = IGN ”; stm

16、t.executeUpdate(s);,Delete,Remove a row from a table delete from category where catg_code = “IGN” remove the IGN category delete from category where catg_code like “I%” remove all rows where catg_code starts with an “I”,Data Definition Commands,Create table add a table to a database Drop Table remove a table from a database Alter Table add or delete column(s),