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JDBC: Java DataBase Connection, an open standard

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• Intro to JDBC

  • What is JDBC:

    JDBC is the acronym for Java Database Connection JDBC is Sun MicroSystem's Java response to the popular MicroSoft's ODBC (Open Database Connection) JDBC provides the capability to access a database server through a set of library functions (similar to the C API) The set of library functions froms an Standardized Application Programming Interface (API) JDBC is now supported by all major database vendors.

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• The java.sql package

  • The JDBC library functions are contained in the following Java package: (Java doc: click here)

    java.sql

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  • Therefore, every JDBC program must import the classes in this package as follows:

    import java.sql.*

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• Structure of JDBC program
  • The basic structure of a JDBC program that accesses a database server is as follows:

    import java.sql.*; <--- import classes in the JDBC package public class myJDBCprogram { .... public static void main(String[] args) throws SQLException { /* ------------------------------------------ These steps are performed ONCE only to setup the communication ------------------------------------------ */ 1. Load the appropriate JDBC communication driver; Analogy: we install a telephone so we can make calls to mySQL 2. Connect to the database Analogy: we dial the mySQL server number.... 3. Create a SQL Statement object to execute query Analogy: we get a (erasable) notpad (to save info) /* ------------------------------------------------------- These steps can be performed any number of times.... ------------------------------------------------------- */ 4. Submit SQL statement for processing and receive back a handle (cursor) to receive result Analogy: we ask a question 5. Retrieve the tuples in the result set (loop !) Analogy: we write down the answer(s) on the notepad /* ------------------------------------------------------- These step is done ONCE when we're done ------------------------------------------------------- */ 6. Cleanup when program is done. Analogy: We get rid of the notepad and the telephone ! } }

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  • NOTE:

    Many of the methods in the JDBC SQL library will throw SQLException when there is an error during the method execution. You must catch the exception using the try/catch statement: try { Use/call a method in java.sql package } catch ( SQLException e ) { statements to execute when there are error(s) } Alternatively, you specify throws SQLException is to each method in your program -- the program will then exit if there is an error: public .... yourMethod( ) throws SQLException { Use/call a method in java.sql package; // Program will exit when the method returns an error... }